Lanefan
Victoria Rules
I'll only run for people I either already know or who have been vouched for by someone I know.The reason for that is the 13 year campaign though. That's not a universal situation. Everyone knows each other really well.
If I'm running an open game at a meet-up I'm a lot more pro-active in having the DM job be also a leadership position then I am with either of my longer term regular groups.
And it hasn't been the same players for all 13 years. There's been turnover - a total of 12* players have each had multiple characters during that time.
* - there was a 13th, but she was a one-session wonder brought in by two existing players; she rolled up a character, stayed for that session, seemed to enjoy it from all I or anyone else could tell, and was never seen or heard from again by any of us.