Update pool creation

src/sim_recon/recon.py

@@ -381,8 +381,11 @@ def run_single_reconstruction(
 ) -> None:
 
     if multiprocessing_pool is None:
+        # `maxtasksperchild=1` is necessary to ensure the child process is cleaned
+        # up between tasks, as the cudasirecon process doesn't fully release memory
+        # afterwards
         pool = multiprocessing.Pool(
-            processes=1 + int(parallel_process),  # 2 processes max
+            processes=2 if parallel_process else 1,  # 2 processes max
             maxtasksperchild=1,
         )
     else:
@@ -393,9 +396,6 @@ def run_single_reconstruction(
         logging_redirect = get_logging_redirect()
         progress_wrapper = get_progress_wrapper()
 
-        # `maxtasksperchild=1` is necessary to ensure the child process is cleaned
-        # up between tasks, as the cudasirecon process doesn't fully release memory
-        # afterwards
         with logging_redirect(), delete_directory_if_empty(processing_directory):
             output_paths: tuple[Path, ...] | None = None
             try:
@@ -564,7 +564,7 @@ def run_reconstructions(
     # afterwards
     with (
         multiprocessing.Pool(
-            processes=1 + int(parallel_process),  # 2 processes max
+            processes=2 if parallel_process else 1,  # 2 processes max
             maxtasksperchild=1,
         ) as pool,
         logging_redirect(),