Have people seen some 3-way (MMF) scenes where instead of the two guys banging the girl and then forcing themselves to both cum on her face right at the end, instead, it's more of a "tag team" where one guy is doing most of the work while the other guy stays in the background. The idea would be that the lead guy would fuck the girl like crazy, shoot his load, and then switch with the other guy... I would think this would give him time to recover, so that the two guys could both do at least two rounds with the girl -- delivering at least four cumshots, more or less at regular intervals.

Personally, I don't like more than one guy fucking the girl at a time, because you end up with lots of male ass on the screen, and because the cameraman/director keeps shifting around trying to figure out where the real action is they should be filming. With the tag-team, it's always very simple to follow the action in the scene, and the camera is focused on what one guy and one girl are doing. And if you see the extra guy in the background, getting his cock sucked by the girl, great... but if not, it's no big deal, because it'll be his turn later.