REF: use CoW helpers more (#53911)

Author: jbrockmendel

pandas/core/internals/blocks.py

@@ -1120,11 +1120,8 @@ def setitem(self, indexer, value, using_cow: bool = False) -> Block:
                     #  test_iloc_setitem_custom_object
                     casted = setitem_datetimelike_compat(values, len(vi), casted)
 
-            if using_cow and self.refs.has_reference():
-                values = values.copy()
-                self = self.make_block_same_class(
-                    values.T if values.ndim == 2 else values
-                )
+            self = self._maybe_copy(using_cow, inplace=True)
+            values = cast(np.ndarray, self.values.T)
             if isinstance(casted, np.ndarray) and casted.ndim == 1 and len(casted) == 1:
                 # NumPy 1.25 deprecation: https://github.com/numpy/numpy/pull/10615
                 casted = casted[0, ...]
@@ -1167,14 +1164,10 @@ def putmask(self, mask, new, using_cow: bool = False) -> list[Block]:
         try:
             casted = np_can_hold_element(values.dtype, new)
 
-            if using_cow and self.refs.has_reference():
-                # Do this here to avoid copying twice
-                values = values.copy()
-                self = self.make_block_same_class(values)
+            self = self._maybe_copy(using_cow, inplace=True)
+            values = cast(np.ndarray, self.values)
 
             putmask_without_repeat(values.T, mask, casted)
-            if using_cow:
-                return [self.copy(deep=False)]
             return [self]
         except LossySetitemError:
             if self.ndim == 1 or self.shape[0] == 1:
@@ -1808,10 +1801,6 @@ def putmask(self, mask, new, using_cow: bool = False) -> list[Block]:
         if new is lib.no_default:
             new = self.fill_value
 
-        values = self.values
-        if values.ndim == 2:
-            values = values.T
-
         orig_new = new
         orig_mask = mask
         new = self._maybe_squeeze_arg(new)
@@ -1822,9 +1811,10 @@ def putmask(self, mask, new, using_cow: bool = False) -> list[Block]:
                 return [self.copy(deep=False)]
             return [self]
 
-        if using_cow and self.refs.has_reference():
-            values = values.copy()
-            self = self.make_block_same_class(values.T if values.ndim == 2 else values)
+        self = self._maybe_copy(using_cow, inplace=True)
+        values = self.values
+        if values.ndim == 2:
+            values = values.T
 
         try:
             # Caller is responsible for ensuring matching lengths