My wife "Vixen" loves the occasional gangbang, though she hates the word and turns her off. As my luck would have it, Vixen between two guys at the same time was normalized from early on. 2 couples making out in cars in high school turned into having sex at the same time as her dorm mate, and by the end of the first year of university she had sucked off two guys (lacrosse players) at the same time, and she liked it. When she studied abroad she finally went all the way when she let a French guy and an Italian guy in her program fuck her in a hostel. She eventually confessed the 3 of them hooked up all weekend like that. True story: after graduated she moved to a Big City and she moved into a house with 3 guys from school. About six months she had already hooked up with each of them to some degree, and the finally ganged up on her a few weeks she was to move to another place. Apparently she enjoyed it because she decided to stay an extra few months through summer "for the pool" ;P
The most men she's sucked off at the same time (a blowbang) is 3. The most men she's had sex "at the same time" is 3. But one time she was in a situation where 2 of us had one round with her before watching 2 others go a round with her. So I guess her max number is 4.
These days, Vixen is willing to occasionally let a 2 on 1 (mfm) situation spontaneously develop. 3 on 1 situations only happen with some prior agreement between us, and at least 2 of the 3 (usually I'm one of them!) are vetted men she knows.