My wife only has sex with complete strangers ... one-time and first-time sex only, then she/we never see any of them afterwards.
In terms of the "most" ever ... she was gangbanged by 7 consecutive guys all in one night at a sex club, I was there to watch and enjoy the show, it was awesome!!! Can't wait to do that again sometime.
I've always told her that I'd like it if she got a regular boyfriend thing going with one other steady guy, but she doesn't like that idea too much ... she prefers one-time fucks with strangers, which of course is okay with me!