How many families per world

I have between 1 and 3 played lots on each of my worlds. I don't have a lot of packs so that is really only about 8 lots total. Thing is, on some of my sims I just have an idea of where I want them to be job/house/family wise, so once they get there they become unplayed sims who are more background decorations (sims my played ones may come across) rather than the ones I play regularly. I've gotten into the habit recently of maxing out jobs on some and then opening a store with them so my other sims (and me) don't have to grind through the same job over and over again to get some of the useful items.