From 6b3ba45ad4cdf57ee601d6e211bc4635afa79b7f Mon Sep 17 00:00:00 2001
From: JoerivanEngelen <joerivanengelen@hotmail.com>
Date: Tue, 16 Dec 2025 17:11:09 +0100
Subject: [PATCH 1/8] Add missing ignore_time_purge_empty arguments

---
 imod/common/utilities/mask.py |  6 ++++--
 imod/mf6/model.py             | 12 ++++++++++--
 imod/mf6/simulation.py        | 14 +++++++++++++-
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/imod/common/utilities/mask.py b/imod/common/utilities/mask.py
index 7e0809145..63bbf5290 100644
--- a/imod/common/utilities/mask.py
+++ b/imod/common/utilities/mask.py
@@ -40,6 +40,7 @@ def _validate_coords_mask(mask: GridDataArray) -> None:
 def _mask_all_models(
     simulation: ISimulation,
     mask: GridDataArray,
+    ignore_time_purge_empty: bool = False,
 ):
     _validate_coords_mask(mask)
     if simulation.is_split():
@@ -54,7 +55,7 @@ def _mask_all_models(
 
     for name in modelnames:
         if is_same_domain(simulation[name].domain, mask):
-            simulation[name].mask_all_packages(mask)
+            simulation[name].mask_all_packages(mask, ignore_time_purge_empty)
         else:
             raise ValueError(
                 "masking can only be applied to simulations when all the models in the simulation use the same grid."
@@ -64,11 +65,12 @@ def _mask_all_models(
 def _mask_all_packages(
     model: IModel,
     mask: GridDataArray,
+    ignore_time_purge_empty: bool = False,
 ):
     _validate_coords_mask(mask)
     for pkgname, pkg in model.items():
         model[pkgname] = pkg.mask(mask)
-    model.purge_empty_packages()
+    model.purge_empty_packages(ignore_time=ignore_time_purge_empty)
 
 
 def mask_package(package: IPackage, mask: GridDataArray) -> IPackage:
diff --git a/imod/mf6/model.py b/imod/mf6/model.py
index ee0de6da6..ffadab4bc 100644
--- a/imod/mf6/model.py
+++ b/imod/mf6/model.py
@@ -697,6 +697,7 @@ def clip_box(
         y_min: Optional[float] = None,
         y_max: Optional[float] = None,
         state_for_boundary: Optional[GridDataArray] = None,
+        ignore_time_purge_empty: bool = False,
     ):
         """
         Clip a model by a bounding box (time, layer, y, x).
@@ -724,6 +725,9 @@ def clip_box(
         state_for_boundary : optional, Union[xr.DataArray, xu.UgridDataArray]
             A grids with states that are used to put as boundary values. This
             model will get a :class:`imod.mf6.ConstantHead`.
+        ignore_time_purge_empty : bool, default False
+            Whether to ignore time dimension when purging empty packages. Can
+            improve performance when clipping models with many time steps.
 
         Returns
         -------
@@ -786,7 +790,7 @@ def clip_box(
         if clipped_boundary_condition is not None:
             clipped[pkg_name] = clipped_boundary_condition
 
-        clipped.purge_empty_packages()
+        clipped.purge_empty_packages(ignore_time=ignore_time_purge_empty)
 
         return clipped
 
@@ -882,6 +886,7 @@ def regrid_like(
     def mask_all_packages(
         self,
         mask: GridDataArray,
+        ignore_time_purge_empty: bool = False,
     ):
         """
         This function applies a mask to all packages in a model. The mask must
@@ -898,9 +903,12 @@ def mask_all_packages(
         mask: xr.DataArray, xu.UgridDataArray of ints
             idomain-like integer array. >0 sets cells to active, 0 sets cells to inactive,
             <0 sets cells to vertical passthrough
+        ignore_time_purge_empty: bool, default False
+            Whether to ignore time dimension when purging empty packages. Can
+            improve performance when masking models with many time steps.
         """
 
-        _mask_all_packages(self, mask)
+        _mask_all_packages(self, mask, ignore_time_purge_empty)
 
     def purge_empty_packages(
         self, model_name: Optional[str] = "", ignore_time: bool = False
diff --git a/imod/mf6/simulation.py b/imod/mf6/simulation.py
index d3c734f5c..220c6bbfe 100644
--- a/imod/mf6/simulation.py
+++ b/imod/mf6/simulation.py
@@ -1202,6 +1202,7 @@ def clip_box(
         y_min: Optional[float] = None,
         y_max: Optional[float] = None,
         states_for_boundary: Optional[dict[str, GridDataArray]] = None,
+        ignore_time_purge_empty: Optional[bool] = None,
     ) -> Modflow6Simulation:
         """
         Clip a simulation by a bounding box (time, layer, y, x).
@@ -1233,6 +1234,11 @@ def clip_box(
             :class:`imod.mf6.ConstantHead`,
             :class:`imod.mf6.GroundwaterTransportModel` will get a
             :class:`imod.mf6.ConstantConcentration` package.
+        ignore_time_purge_empty: bool, default None
+            If True, only the first timestep is validated. This increases
+            performance for packages with a time dimensions over which changes
+            of cell activity are not expected. If None, the value of the
+            validation context is of the simulation is used.
 
         Returns
         -------
@@ -1276,6 +1282,8 @@ def clip_box(
             raise ValueError(
                 "Unable to clip simulation. Clipping can only be done on simulations that have a single flow model ."
             )
+        if ignore_time_purge_empty is None:
+            ignore_time_purge_empty = self._validation_context.ignore_time
         for model_name, model in self.get_models().items():
             supported, error_with_object = model._is_clipping_supported()
             if not supported:
@@ -1301,6 +1309,7 @@ def clip_box(
                     y_min=y_min,
                     y_max=y_max,
                     state_for_boundary=state_for_boundary,
+                    ignore_time_purge_empty=ignore_time_purge_empty,
                 )
             elif isinstance(value, Package):
                 clipped[key] = value.clip_box(
@@ -1688,6 +1697,7 @@ def _has_one_flow_model(self) -> bool:
     def mask_all_models(
         self,
         mask: GridDataArray,
+        ignore_time_purge_empty: Optional[bool] = None,
     ) -> None:
         """
         This function applies a mask to all models in a simulation, provided they use
@@ -1713,7 +1723,9 @@ def mask_all_models(
         mask should be an idomain-like array, i.e. it should have the same shape
         as the model and contain integer values.
         """
-        _mask_all_models(self, mask)
+        if ignore_time_purge_empty is None:
+            ignore_time_purge_empty = self._validation_context.ignore_time
+        _mask_all_models(self, mask, ignore_time_purge_empty)
 
     @classmethod
     @standard_log_decorator()

From 6de94c0855737b22e42e0ca25e93dbb57f87d4b3 Mon Sep 17 00:00:00 2001
From: JoerivanEngelen <joerivanengelen@hotmail.com>
Date: Tue, 16 Dec 2025 17:12:24 +0100
Subject: [PATCH 2/8] Remove underscore in helper functions used outside module

---
 imod/common/utilities/mask.py | 4 ++--
 imod/mf6/model.py             | 4 ++--
 imod/mf6/simulation.py        | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/imod/common/utilities/mask.py b/imod/common/utilities/mask.py
index 63bbf5290..b0199cb30 100644
--- a/imod/common/utilities/mask.py
+++ b/imod/common/utilities/mask.py
@@ -37,7 +37,7 @@ def _validate_coords_mask(mask: GridDataArray) -> None:
         )
 
 
-def _mask_all_models(
+def mask_all_models(
     simulation: ISimulation,
     mask: GridDataArray,
     ignore_time_purge_empty: bool = False,
@@ -62,7 +62,7 @@ def _mask_all_models(
             )
 
 
-def _mask_all_packages(
+def mask_all_packages(
     model: IModel,
     mask: GridDataArray,
     ignore_time_purge_empty: bool = False,
diff --git a/imod/mf6/model.py b/imod/mf6/model.py
index ffadab4bc..f84d8bca8 100644
--- a/imod/mf6/model.py
+++ b/imod/mf6/model.py
@@ -22,7 +22,7 @@
 from imod.common.serializer import EngineType
 from imod.common.statusinfo import NestedStatusInfo, StatusInfo, StatusInfoBase
 from imod.common.utilities.clip import clip_box_dataset
-from imod.common.utilities.mask import _mask_all_packages
+from imod.common.utilities.mask import mask_all_packages
 from imod.common.utilities.regrid import _regrid_like
 from imod.common.utilities.schemata import (
     concatenate_schemata_dicts,
@@ -908,7 +908,7 @@ def mask_all_packages(
             improve performance when masking models with many time steps.
         """
 
-        _mask_all_packages(self, mask, ignore_time_purge_empty)
+        mask_all_packages(self, mask, ignore_time_purge_empty)
 
     def purge_empty_packages(
         self, model_name: Optional[str] = "", ignore_time: bool = False
diff --git a/imod/mf6/simulation.py b/imod/mf6/simulation.py
index 220c6bbfe..27c734ac4 100644
--- a/imod/mf6/simulation.py
+++ b/imod/mf6/simulation.py
@@ -24,7 +24,7 @@
 from imod.common.serializer import EngineType
 from imod.common.statusinfo import NestedStatusInfo
 from imod.common.utilities.dataclass_type import DataclassType
-from imod.common.utilities.mask import _mask_all_models
+from imod.common.utilities.mask import mask_all_models
 from imod.common.utilities.regrid import _regrid_like
 from imod.common.utilities.version import (
     get_version,
@@ -1725,7 +1725,7 @@ def mask_all_models(
         """
         if ignore_time_purge_empty is None:
             ignore_time_purge_empty = self._validation_context.ignore_time
-        _mask_all_models(self, mask, ignore_time_purge_empty)
+        mask_all_models(self, mask, ignore_time_purge_empty)
 
     @classmethod
     @standard_log_decorator()

From 4ca30365d43f02af368101ea7903a27b725a42f0 Mon Sep 17 00:00:00 2001
From: JoerivanEngelen <joerivanengelen@hotmail.com>
Date: Tue, 16 Dec 2025 17:24:53 +0100
Subject: [PATCH 3/8] Add some extra test cases where ignore_time_purge_empty
 is set to True and False.

---
 imod/tests/test_mf6/test_mf6_LHM.py             | 2 +-
 imod/tests/test_mf6/test_mf6_mask_simulation.py | 5 +++--
 imod/tests/test_mf6/test_mf6_model_masking.py   | 4 +++-
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/imod/tests/test_mf6/test_mf6_LHM.py b/imod/tests/test_mf6/test_mf6_LHM.py
index 44a8812c9..6fa13a852 100644
--- a/imod/tests/test_mf6/test_mf6_LHM.py
+++ b/imod/tests/test_mf6/test_mf6_LHM.py
@@ -78,7 +78,7 @@ def cleanup_mf6_sim(simulation: Modflow6Simulation) -> None:
         pkg.dataset.load()
 
     mask = model.domain
-    simulation.mask_all_models(mask)
+    simulation.mask_all_models(mask, ignore_time_purge_empty=True)
     dis = model["dis"]
 
     pkgs_to_cleanup = [
diff --git a/imod/tests/test_mf6/test_mf6_mask_simulation.py b/imod/tests/test_mf6/test_mf6_mask_simulation.py
index 575693503..c3e6b50fa 100644
--- a/imod/tests/test_mf6/test_mf6_mask_simulation.py
+++ b/imod/tests/test_mf6/test_mf6_mask_simulation.py
@@ -8,14 +8,15 @@
 import imod
 from imod.tests.fixtures.mf6_modelrun_fixture import assert_simulation_can_run
 
-
+@pytest.mark.parametrize("ignore_time", [True, False])
 def test_mask_simulation(
     tmp_path: Path,
     flow_transport_simulation: imod.mf6.Modflow6Simulation,
+    ignore_time: bool,
 ):
     mask = deepcopy(flow_transport_simulation["flow"].domain)
     mask.loc[1, 0.5, 15] = 0
-    flow_transport_simulation.mask_all_models(mask)
+    flow_transport_simulation.mask_all_models(mask, ignore_time_purge_empty=ignore_time)
     assert (
         flow_transport_simulation["flow"].domain.sel({"layer": 1, "y": 0.5, "x": 15})
         == 0
diff --git a/imod/tests/test_mf6/test_mf6_model_masking.py b/imod/tests/test_mf6/test_mf6_model_masking.py
index ed8bbb71a..68c12397f 100644
--- a/imod/tests/test_mf6/test_mf6_model_masking.py
+++ b/imod/tests/test_mf6/test_mf6_model_masking.py
@@ -266,11 +266,13 @@ def test_mask_with_time_coordinate(
 @pytest.mark.parametrize(
     "inactivity_marker", [0, -1]
 )  # 0 = inactive, -1 = vertical passthrough
+@pytest.mark.parametrize("ignore_time_purge_empty", [True, False])
 def test_mask_structured(
     tmp_path: Path,
     structured_flow_model: GroundwaterFlowModel,
     mask_cells: list[tuple[int, int, int]],
     inactivity_marker: int,
+    ignore_time_purge_empty: bool,
 ):
     # Arrange
     # add a well to the model
@@ -291,7 +293,7 @@ def test_mask_structured(
         mask.values[*cell] = inactivity_marker
 
     # Act
-    structured_flow_model.mask_all_packages(mask)
+    structured_flow_model.mask_all_packages(mask, ignore_time_purge_empty=ignore_time_purge_empty)
 
     # Assert
     unique, counts = np.unique(

From 315d9288803666dc40bab33083811e34ebd05ddb Mon Sep 17 00:00:00 2001
From: JoerivanEngelen <joerivanengelen@hotmail.com>
Date: Tue, 16 Dec 2025 17:34:00 +0100
Subject: [PATCH 4/8] Expand tests

---
 imod/tests/test_mf6/test_mf6_mask_simulation.py | 1 +
 imod/tests/test_mf6/test_mf6_model_masking.py   | 4 +++-
 imod/tests/test_mf6/test_mf6_simulation.py      | 8 ++++++++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/imod/tests/test_mf6/test_mf6_mask_simulation.py b/imod/tests/test_mf6/test_mf6_mask_simulation.py
index c3e6b50fa..6058a49b1 100644
--- a/imod/tests/test_mf6/test_mf6_mask_simulation.py
+++ b/imod/tests/test_mf6/test_mf6_mask_simulation.py
@@ -8,6 +8,7 @@
 import imod
 from imod.tests.fixtures.mf6_modelrun_fixture import assert_simulation_can_run
 
+
 @pytest.mark.parametrize("ignore_time", [True, False])
 def test_mask_simulation(
     tmp_path: Path,
diff --git a/imod/tests/test_mf6/test_mf6_model_masking.py b/imod/tests/test_mf6/test_mf6_model_masking.py
index 68c12397f..94355e352 100644
--- a/imod/tests/test_mf6/test_mf6_model_masking.py
+++ b/imod/tests/test_mf6/test_mf6_model_masking.py
@@ -293,7 +293,9 @@ def test_mask_structured(
         mask.values[*cell] = inactivity_marker
 
     # Act
-    structured_flow_model.mask_all_packages(mask, ignore_time_purge_empty=ignore_time_purge_empty)
+    structured_flow_model.mask_all_packages(
+        mask, ignore_time_purge_empty=ignore_time_purge_empty
+    )
 
     # Assert
     unique, counts = np.unique(
diff --git a/imod/tests/test_mf6/test_mf6_simulation.py b/imod/tests/test_mf6/test_mf6_simulation.py
index 81b9e827c..06a9be30c 100644
--- a/imod/tests/test_mf6/test_mf6_simulation.py
+++ b/imod/tests/test_mf6/test_mf6_simulation.py
@@ -278,6 +278,14 @@ def test_write_circle_model_twice(circle_model, tmp_path):
     assert len(diff.right_only) == 0
 
 
+@pytest.mark.parametrize("ignore_time_purge_empty", [True, False])
+def test_simulation_clip_box__ignore_time(circle_model, ignore_time_purge_empty):
+    simulation = circle_model
+    simulation.clip_box(
+        y_min=-50, y_max=0, ignore_time_purge_empty=ignore_time_purge_empty
+    )
+
+
 def test_simulation_clip_box__validation_settings_preserved(circle_model):
     simulation = circle_model
     simulation.set_validation_settings(

From 7ee12fdd361a33736970034b802d40a1ee1cc0e7 Mon Sep 17 00:00:00 2001
From: JoerivanEngelen <joerivanengelen@hotmail.com>
Date: Tue, 16 Dec 2025 17:41:19 +0100
Subject: [PATCH 5/8] Update changelog

---
 docs/api/changelog.rst | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/docs/api/changelog.rst b/docs/api/changelog.rst
index 82a3f5d96..acadd5334 100644
--- a/docs/api/changelog.rst
+++ b/docs/api/changelog.rst
@@ -9,6 +9,15 @@ The format is based on `Keep a Changelog`_, and this project adheres to
 [Unreleased]
 ------------
 
+Added
+~~~~~
+
+- Added ``ignore_time_purge_empty`` argument to
+  :meth:`imod.mf6.Modflow6Simulation.mask_all_models` and
+  :meth:`imod.mf6.Modflow6Simulation.clip_box` to consider a package empty if
+  its first times step is all nodata. This can save a lot of clipping or masking
+  transient models with many timesteps.
+
 Fixed
 ~~~~~
 

From ab16d186a77867cdad240bde564bd7d5b4f85116 Mon Sep 17 00:00:00 2001
From: JoerivanEngelen <joerivanengelen@hotmail.com>
Date: Mon, 5 Jan 2026 09:33:22 +0100
Subject: [PATCH 6/8] Improve ignore_time_purge_empty explanations.

---
 imod/mf6/model.py      |  9 +++++++--
 imod/mf6/simulation.py | 36 +++++++++++++++++++++++++-----------
 2 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/imod/mf6/model.py b/imod/mf6/model.py
index f84d8bca8..97c464be5 100644
--- a/imod/mf6/model.py
+++ b/imod/mf6/model.py
@@ -726,8 +726,13 @@ def clip_box(
             A grids with states that are used to put as boundary values. This
             model will get a :class:`imod.mf6.ConstantHead`.
         ignore_time_purge_empty : bool, default False
-            Whether to ignore time dimension when purging empty packages. Can
-            improve performance when clipping models with many time steps.
+            Whether to ignore the time dimension when purging empty packages.
+            Can improve performance when clipping models with many time steps.
+            Clipping models can cause package data with all nans. These packages
+            are considered empty and need to be removed. However, checking all
+            timesteps for each package is a costly operation. Therefore, this
+            option can be set to True to only check the first timestep. Defaults
+            to False.
 
         Returns
         -------
diff --git a/imod/mf6/simulation.py b/imod/mf6/simulation.py
index 27c734ac4..c5cfea7f7 100644
--- a/imod/mf6/simulation.py
+++ b/imod/mf6/simulation.py
@@ -1234,11 +1234,14 @@ def clip_box(
             :class:`imod.mf6.ConstantHead`,
             :class:`imod.mf6.GroundwaterTransportModel` will get a
             :class:`imod.mf6.ConstantConcentration` package.
-        ignore_time_purge_empty: bool, default None
-            If True, only the first timestep is validated. This increases
-            performance for packages with a time dimensions over which changes
-            of cell activity are not expected. If None, the value of the
-            validation context is of the simulation is used.
+        ignore_time_purge_empty: optional, bool, default None
+            Whether to ignore the time dimension when purging empty packages.
+            Can improve performance when clipping models with many time steps.
+            Clipping models can cause package data with all nans. These packages
+            are considered empty and need to be removed. However, checking all
+            timesteps for each package is a costly operation. Therefore, this
+            option can be set to True to only check the first timestep. If None,
+            the value of the validation settings of the simulation are used.
 
         Returns
         -------
@@ -1407,11 +1410,14 @@ def split(
             similar shape as a layer in the domain. The values in the array
             indicate to which partition a cell belongs. The values should be
             zero or greater.
-        ignore_time_purge_empty: bool, default None
-            If True, only the first timestep is validated. This increases
-            performance for packages with a time dimensions over which changes
-            of cell activity are not expected. If None, the value of the
-            validation context is of the simulation is used.
+        ignore_time_purge_empty: optional, bool, default None
+            Whether to ignore the time dimension when purging empty packages.
+            Can improve performance when splitting models with many time steps.
+            Splitting models can cause package data with all nans. These packages
+            are considered empty and need to be removed. However, checking all
+            timesteps for each package is a costly operation. Therefore, this
+            option can be set to True to only check the first timestep. If None,
+            the value of the validation settings of the simulation are used.
 
         Returns
         -------
@@ -1712,7 +1718,15 @@ def mask_all_models(
         mask: xr.DataArray, xu.UgridDataArray of ints
             idomain-like integer array. >0 sets cells to active, 0 sets cells to inactive,
             <0 sets cells to vertical passthrough
-
+        ignore_time_purge_empty : bool, default False
+            Whether to ignore the time dimension when purging empty packages.
+            Can improve performance when masking models with many time steps.
+            Masking models can cause package data with all nans. These packages
+            are considered empty and need to be removed. However, checking all
+            timesteps for each package is a costly operation. Therefore, this
+            option can be set to True to only check the first timestep. Defaults
+            to False.
+            
         Examples
         --------
         To mask all models in a simulation, you can use the following code:

From 9aceb46e99d5806cd1335c03226afbaa2638d4be Mon Sep 17 00:00:00 2001
From: JoerivanEngelen <joerivanengelen@hotmail.com>
Date: Mon, 5 Jan 2026 10:14:42 +0100
Subject: [PATCH 7/8] Add note to avoid wasting time on catching timeouts with
 a xfail again.

---
 imod/tests/test_mf6/test_mf6_rch.py | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/imod/tests/test_mf6/test_mf6_rch.py b/imod/tests/test_mf6/test_mf6_rch.py
index b8b11f64e..992d299a0 100644
--- a/imod/tests/test_mf6/test_mf6_rch.py
+++ b/imod/tests/test_mf6/test_mf6_rch.py
@@ -297,8 +297,16 @@ def test_validate_false():
 
 @pytest.mark.timeout(10, method="thread")
 def test_ignore_time_validation():
-    # Create a large recharge dataset with a time dimension. This is to test the
-    # performance of the validation when ignore_time_no_data is True.
+    """
+    Create a large recharge dataset with a time dimension. This is to test the
+    performance of the validation when ignore_time_no_data is True. 
+    NOTE: There currently is no easy way to test the opposite (i.e.,
+    ignore_time_no_data is False, then catch timeout with an pytest xfail
+    marker), because the timeout will terminate the test run with an error when
+    using dask instead of a fail. Somewhat relevant issue:
+    https://github.com/pytest-dev/pytest-timeout/issues/181
+    """
+    # Arrange
     rng = dask.array.random.default_rng()
     layer = [1, 2, 3]
     template = imod.util.empty_3d(1.0, 0.0, 1000.0, 1.0, 0.0, 1000.0, layer)

From 9a573a880b84568fa7086b2167cd9512c3b7bc29 Mon Sep 17 00:00:00 2001
From: JoerivanEngelen <joerivanengelen@hotmail.com>
Date: Mon, 5 Jan 2026 10:24:47 +0100
Subject: [PATCH 8/8] format

---
 imod/mf6/simulation.py              | 2 +-
 imod/tests/test_mf6/test_mf6_rch.py | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/imod/mf6/simulation.py b/imod/mf6/simulation.py
index c5cfea7f7..976219fbd 100644
--- a/imod/mf6/simulation.py
+++ b/imod/mf6/simulation.py
@@ -1726,7 +1726,7 @@ def mask_all_models(
             timesteps for each package is a costly operation. Therefore, this
             option can be set to True to only check the first timestep. Defaults
             to False.
-            
+
         Examples
         --------
         To mask all models in a simulation, you can use the following code:
diff --git a/imod/tests/test_mf6/test_mf6_rch.py b/imod/tests/test_mf6/test_mf6_rch.py
index 992d299a0..ae8c8037f 100644
--- a/imod/tests/test_mf6/test_mf6_rch.py
+++ b/imod/tests/test_mf6/test_mf6_rch.py
@@ -299,7 +299,7 @@ def test_validate_false():
 def test_ignore_time_validation():
     """
     Create a large recharge dataset with a time dimension. This is to test the
-    performance of the validation when ignore_time_no_data is True. 
+    performance of the validation when ignore_time_no_data is True.
     NOTE: There currently is no easy way to test the opposite (i.e.,
     ignore_time_no_data is False, then catch timeout with an pytest xfail
     marker), because the timeout will terminate the test run with an error when