The files in the library are the ones you see, the ones you can use directly. In case you acquired some other package, one with, say, backgrounds, or wood textures, then you can put this in the Runtime>Materials folder so that it is not too difficult to find. As for the runtimes you suggest...yes and no. It depends. In case P5 asks for a certain file, then note it, and copy it from the basic Runtime into the new one. Example: V2 upgrade came without the milwom object that came with Zygote V1. It is also best to keep the daz people files in the original runtime. You can have runtimes for people, animals, scifi, architecture, fantasy, realism,...just like you fancy. And if you ever find you have too many, you can merge them easily. It sounds great to have many runtimes, but I personally reduced the number drastically. One I find very useful is one for freestuff. Try it out, and if it is what you hoped it was, add it to the "real" one.

I have tried prudent planning long enough. From now I'll be mad. (Rumi)