I have multiple runtimes (M4, V4, Gen3, Locations, Vehicles etc) plus I also have a Project Runtime (where all my own materials, poses and assembled characters go, under folders named for the project... this means if I go back through my images I know which folder the character is in). I also have a Test Runtime (not just for freebies, but also for the auto installers so I can rearrange the content to suit my file structure before dragging and dropping onto the appropriate runtime) as well as a separate hair runtime.