bpy: Location to save your python script files

Default installation location. 

   In python console, enter >>>print(bpy);

   Outputs should be something like below.

   <module 'bpy' from '...\Blender Foundation\\Blender 2.81\\2.81\\scripts\\modules\\bpy\\__init__.py'>
   Save your python files in "modules" folder.

Reloading your python files.
   import importlib as iLib;iLib.reload(your python script file name without extension);
   e.g. iLib.reload(i3d); to reload i3d.py in modules folder.