I've been in one and I've seen the girl use only 2 holes and she was pleasing 4 guys at the same time!!! Double team in her pussy and double team in her mouth!!!About the math... don't forget 1 girl can please at least 4-5 guys at the same time, 3 holes and 2 hands...
Anyway, I'm out of those games but the mathematical aspect should be reconsidered.
You have to see it as an experience and leave your barriers at the door... touching tips isn't a problem for me!!! You use the girl as your fuck doll and that's it... no sentimental attachment there...
I've tried it a few times but to be honest... not my thing. But I had to try it at least once!!!