I have 3-4 main chars, and each of them have a group of primary supporting chars that match them. So not sure how you count that. Those supporting chars are pretty fleshed out, and critical to the story, but then I also have a layer of "that guy in the background that makes the scene real"
For example you might have 2 chars go to a gas station in NJ were gas attendant helps them. That attendant needs to be there (self serve is illegal in NJ) for the scene to be believable, but he is more of a prop then a character. Probably most good stories have a ton of those kinds of characters.