Whatever makes your searches easiest.  You can merge all your Vicky's into one runtime or issue them into their own.  There is no ironclad guideline.  For instance, I have a runtime for each of my main characters although the base models reside within the main app's runtime.  I also have a separate folder for hair, poses, and creatures.  There is a specialized folder for Superhero content, as well as a projects runtime for one time use.