Fellow gamemasters, I need your input; I'm trying to create a game preparation formula that can be used for most games. For this, I need some input from you. I'd appreciate if you can tell a bit about your game preparations, mainly how many and how well prepared npc's you need.
So - how many npc's do you need for a rpg session? We're assuming that the session takes perhaps 4-6 hours using a system where combats (at least most of them) don't take 1+h and the game takes place in an environment in which social contacts are meaningful. I want numbers that lets you run a game with no shortage of npc's even if players get creative (but not intentionally trying to meet as many characters as possible). The format I have in my mind is a semi-sandbox that's supposed to be enough for one session's needs.
-How many detailed npc's, like main villain, his right hand etc?
-How many less detailed npc's - just statistics with little details or perhaps a lot of information or other details but with little or no statistics?
-How many npc's with just a few details and a function?
Do you think this is a good categorization for detail level of npc's, or do you have a better suggestion?