I have 6. Played for several hours after I made them. All but 2 have shown up during that time. Literally, not once out of all that time have those two shown up once. That's beyond just random.
I don't think it has any effect. One of my NPCs has no weapon or cloths and shows up often on all levels. Order of creation may have something to do with it, but I really have no clue.
