diff --git a/pandas/_libs/lib.pyx b/pandas/_libs/lib.pyx
index b8d79d0835fb8..4b423175172d2 100644
--- a/pandas/_libs/lib.pyx
+++ b/pandas/_libs/lib.pyx
@@ -2440,6 +2440,9 @@ class NoDefault(Enum):
     # 2) because mypy does not understand singletons
     no_default = "NO_DEFAULT"
 
+    def __repr__(self) -> str:
+        return "<no_default>"
+
 
 # Note: no_default is exported to the public API in pandas.api.extensions
 no_default = NoDefault.no_default  # Sentinel indicating the default value.
diff --git a/pandas/core/base.py b/pandas/core/base.py
index 18fc76fe79a5a..b0c2af89ad0c7 100644
--- a/pandas/core/base.py
+++ b/pandas/core/base.py
@@ -1164,7 +1164,7 @@ def is_monotonic_decreasing(self) -> bool:
 
         return Index(self).is_monotonic_decreasing
 
-    def memory_usage(self, deep=False):
+    def _memory_usage(self, deep: bool = False) -> int:
         """
         Memory usage of the values.
 
diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
index 29c2f7cfcf00d..c3f3476618bf0 100644
--- a/pandas/core/indexes/base.py
+++ b/pandas/core/indexes/base.py
@@ -12,7 +12,6 @@
     FrozenSet,
     Hashable,
     List,
-    NewType,
     Optional,
     Sequence,
     Set,
@@ -195,9 +194,6 @@
 _o_dtype = np.dtype("object")
 
 
-_Identity = NewType("_Identity", object)
-
-
 def disallow_kwargs(kwargs: Dict[str, Any]):
     if kwargs:
         raise TypeError(f"Unexpected keyword arguments {repr(set(kwargs))}")
@@ -4405,9 +4401,9 @@ def _get_engine_target(self) -> np.ndarray:
         # ndarray]", expected "ndarray")
         return self._values  # type: ignore[return-value]
 
-    @doc(IndexOpsMixin.memory_usage)
+    @doc(IndexOpsMixin._memory_usage)
     def memory_usage(self, deep: bool = False) -> int:
-        result = super().memory_usage(deep=deep)
+        result = self._memory_usage(deep=deep)
 
         # include our engine hashtable
         result += self._engine.sizeof(deep=deep)
diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index 944844dfbbb5b..e605486e0044e 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -207,6 +207,7 @@ def is_bool(self) -> bool:
     def external_values(self):
         return external_values(self.values)
 
+    @final
     def internal_values(self):
         """
         The array that Series._values returns (internal values).
@@ -593,8 +594,6 @@ def astype(self, dtype, copy: bool = False, errors: str = "raise"):
         Block
         """
         values = self.values
-        if values.dtype.kind in ["m", "M"]:
-            values = self.array_values
 
         new_values = astype_array_safe(values, dtype, copy=copy, errors=errors)
 
@@ -1763,10 +1762,6 @@ def is_view(self) -> bool:
         # check the ndarray values of the DatetimeIndex values
         return self.values._ndarray.base is not None
 
-    def internal_values(self):
-        # Override to return DatetimeArray and TimedeltaArray
-        return self.values
-
     def get_values(self, dtype: Optional[DtypeObj] = None) -> np.ndarray:
         """
         return object dtype as boxed values, such as Timestamps/Timedelta
@@ -1878,7 +1873,6 @@ class DatetimeTZBlock(ExtensionBlock, DatetimeLikeBlockMixin):
     is_extension = True
     is_numeric = False
 
-    internal_values = Block.internal_values
     diff = DatetimeBlock.diff
     where = DatetimeBlock.where
     putmask = DatetimeLikeBlockMixin.putmask
diff --git a/pandas/core/internals/managers.py b/pandas/core/internals/managers.py
index de0a5687aeb8b..3c8d942554575 100644
--- a/pandas/core/internals/managers.py
+++ b/pandas/core/internals/managers.py
@@ -1085,17 +1085,11 @@ def value_getitem(placement):
         else:
             if value.ndim == 2:
                 value = value.T
-
-            if value.ndim == self.ndim - 1:
-                value = ensure_block_shape(value, ndim=2)
-
-                def value_getitem(placement):
-                    return value
-
             else:
+                value = ensure_block_shape(value, ndim=2)
 
-                def value_getitem(placement):
-                    return value[placement.indexer]
+            def value_getitem(placement):
+                return value[placement.indexer]
 
             if value.shape[1:] != self.shape[1:]:
                 raise AssertionError(
diff --git a/pandas/core/series.py b/pandas/core/series.py
index 27ebf7f228bc0..4ade9992e9e3e 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -4609,7 +4609,7 @@ def shift(self, periods=1, freq=None, axis=0, fill_value=None) -> Series:
             periods=periods, freq=freq, axis=axis, fill_value=fill_value
         )
 
-    def memory_usage(self, index=True, deep=False):
+    def memory_usage(self, index: bool = True, deep: bool = False) -> int:
         """
         Return the memory usage of the Series.
 
@@ -4658,7 +4658,7 @@ def memory_usage(self, index=True, deep=False):
         >>> s.memory_usage(deep=True)
         244
         """
-        v = super().memory_usage(deep=deep)
+        v = self._memory_usage(deep=deep)
         if index:
             v += self.index.memory_usage(deep=deep)
         return v