diff --git a/pandas/core/strings/accessor.py b/pandas/core/strings/accessor.py
index 05e1a36877e06..5ec4de4ee792b 100644
--- a/pandas/core/strings/accessor.py
+++ b/pandas/core/strings/accessor.py
@@ -423,7 +423,7 @@ def cons_row(x):
                 result.name = name
             return result
 
-    def _get_series_list(self, others):
+    def _get_series_list(self, others) -> list[Series]:
         """
         Auxiliary function for :meth:`str.cat`. Turn potentially mixed input
         into a list of Series (elements without an index must match the length
@@ -474,8 +474,8 @@ def _get_series_list(self, others):
                     for x in others
                 ):
                     los: list[Series] = []
-                    while others:  # iterate through list and append each element
-                        los = los + self._get_series_list(others.pop(0))
+                    for other in others:
+                        los.extend(self._get_series_list(other))
                     return los
                 # ... or just strings
                 elif all(not is_list_like(x) for x in others):
diff --git a/pandas/plotting/_matplotlib/tools.py b/pandas/plotting/_matplotlib/tools.py
index d5624aecd1215..5ebbdf886eb32 100644
--- a/pandas/plotting/_matplotlib/tools.py
+++ b/pandas/plotting/_matplotlib/tools.py
@@ -1,7 +1,11 @@
 # being a bit too dynamic
 from __future__ import annotations
 
-from math import ceil
+from math import (
+    ceil,
+    floor,
+    log2,
+)
 from typing import TYPE_CHECKING
 import warnings
 
@@ -126,9 +130,7 @@ def _get_layout(
     try:
         return layouts[nplots]
     except KeyError:
-        k = 1
-        while k**2 < nplots:
-            k += 1
+        k = floor(log2(nplots))
 
         if (k - 1) * k >= nplots:
             return k, (k - 1)
diff --git a/pandas/tseries/holiday.py b/pandas/tseries/holiday.py
index bf4ec2e551f01..b9ef557cb1d15 100644
--- a/pandas/tseries/holiday.py
+++ b/pandas/tseries/holiday.py
@@ -116,9 +116,8 @@ def next_workday(dt: datetime) -> datetime:
     returns next workday used for observances
     """
     dt += timedelta(days=1)
-    while dt.weekday() > 4:
-        # Mon-Fri are 0-4
-        dt += timedelta(days=1)
+    # Mon-Fri are 0-4
+    dt += timedelta(days=max(dt.weekday() - 4, 0))
     return dt
 
 
@@ -127,9 +126,8 @@ def previous_workday(dt: datetime) -> datetime:
     returns previous workday used for observances
     """
     dt -= timedelta(days=1)
-    while dt.weekday() > 4:
-        # Mon-Fri are 0-4
-        dt -= timedelta(days=1)
+    # Mon-Fri are 0-4
+    dt -= timedelta(days=max(dt.weekday() - 4, 0))
     return dt