Since NL, the game really doesn't mind how much you subfolder (within the limits, really, or what Windows can cope with, so just avoid very long folder names). Even in the BG, you could folder and subfolder objects, walls, floors, etc., but bodyshop stuff had to be in the main Downloads folder - they made this sub-folderable as well in NL. Unless, like BO, you have De Luxe, you can also place walls, floors, terrain paints and roofs in the main TS2 folder and they will work perfectly. (In actual fact, I have had cc still not added to the main Downloads folder, but in a house folder in Packaged Lots (because I haven't actually used the house yet) and the cc still shows in my game! It seems the game doesn't really mind where the stuff is, so long, of course, as it is somewhere in the TS2 directory... the only thing you do have to be really careful about is that you put collection files into Collections if you want the collection for a set to show up.