Even genuinely bit characters who appear to do a specific act that one person has to do -- start the cheers or the boos, hail the hero, grab the sword -- aren't that difficult since they blur in with the crowd or other forms of scenery when they aren't committing the act.
It's the minor characters. Not the hero. Not his best friends and companions. But since he's, say, going to school, or attending court, there will be people around that he knows. Crowds, yes, but also people he interacts with regularly, and who fill out the local color, but who can't be made too significant. They need names, because the POV character knows their names. But they can't reappear too often, not only because they will start to gain significance whether you want it or not, but because you want new characters to appear in order to create the suggestion of there being lots and lots of people about.
It's enough to make you look longing at the quest, where the major characters get to deal with bit characters who will never make it to minor because the quest goes on without them and so they can't appear enough.