I am currently working on two different sites.
Site 1 Assets are stored in folder \Site 1\assets\
Site 2 Assets are stored in folder \Site 2\assets\
Mostly pictures, but not only pictures.
If I work on site 1 and add pictures the default folder will be whichever folder I last used. Likewise with Site 2, so I waste time browsing to change the folder each time.
I really don't want to mix assets from more than one site in one shared assets folder.
Each site should remember its own assets folder, or last used folder for inserting images, linking to PDF files, etc.