I have this folder in my Mods unchanged as it is presented here so for me everything works ok I leave it like this. If you have a weak computer you can delete images and remove subfolders, placing everything in one pile as you prefer. You can also leave all the default versions of meshes without choosing one of them, because anyway only 1 version of them will be shown in the game. My game displays the one that is higher than the rest in alphabetical order. You can also remove if you want all the 18+ default meshes versions (naked bottoms, tops marked "default") if you have Wicked Whims installed (it has Body Selector). 

Advisable not to place this folder deep in subfolders, especially if something is not displayed in the game.

Also, previous versions of my mods (old duplicates) can be removed using these programs Sims Mod Assistant / Sims 4 Mod Manager or any other.