diff --git a/README.md b/README.md
index 83c9303..ac08053 100644
--- a/README.md
+++ b/README.md
@@ -18,12 +18,12 @@ $ pip install chronify
 
 To use Apache Spark via Apache Thrift Server as the backend:
 ```
-$ pip install chronify --group=pyhive
+$ pip install "chronify[spark]"
 ```
 
 ## Developer installation
 ```
-$ pip install -e ".[dev]" --group=pyhive
+$ pip install -e ".[dev,spark]"
 ```
 
 Please install `pre-commit` so that your code is checked before making commits.
diff --git a/docs/how_tos/getting_started/installation.md b/docs/how_tos/getting_started/installation.md
index ab922a7..398dce1 100644
--- a/docs/how_tos/getting_started/installation.md
+++ b/docs/how_tos/getting_started/installation.md
@@ -38,9 +38,10 @@ To use DuckDB or SQLite as the backend:
 ```
 
 To use Apache Spark via Apache Thrift Server as the backend, you must install pyhive.
+This command will install the necessary dependencies.
 
 ```{eval-rst}
 .. code-block:: console
 
-    $ pip install chronify --group=pyhive
+    $ pip install "chronify[spark]"
 ```
diff --git a/docs/how_tos/spark_backend.md b/docs/how_tos/spark_backend.md
index 1df45c6..5e893bf 100644
--- a/docs/how_tos/spark_backend.md
+++ b/docs/how_tos/spark_backend.md
@@ -4,7 +4,7 @@ scripts for UNIX operating systems (not Windows).
 
 ## Install chronify with Spark support
 ```
-$ pip install chronify --group=pyhive
+$ pip install "chronify[spark]"
 ```
 
 ## Installation on a development computer
diff --git a/src/chronify/datetime_range_generator.py b/src/chronify/datetime_range_generator.py
index b030e68..87574f4 100644
--- a/src/chronify/datetime_range_generator.py
+++ b/src/chronify/datetime_range_generator.py
@@ -120,10 +120,9 @@ def __init__(
     def _list_timestamps(self, time_zone: Optional[tzinfo]) -> list[datetime]:
         """always return tz-naive timestamps relative to input time_zone"""
         if self._model.start_time_is_tz_naive():
-            if time_zone:
-                start = self._model.start.replace(tzinfo=time_zone)
-            else:
-                start = None
+            # For clock-time-aligned data, iterate naively without timezone conversion.
+            # All timezones get the same clock times (e.g., midnight everywhere).
+            start = None
         else:
             if time_zone:
                 start = self._model.start.astimezone(time_zone)