^^^
Usually it's the guys who do most of the fucking. And they are the ones who are liable to get exhausted. That's why I like to see at least two guys for every lady. Two or more guys usually give the lady a much better no-holes-barred ride than one guy with one dick can ever do.
Perhaps Jasmine Byrne in Ganbangers Ball gets tired out servicing her 12 double-dicking guys.

Naomi in Gang Bang #5 also seems to be exhausted at the end of her scene. And it's no wonder. She goes through a big house full of rooms with horny guys in hot pursuit banging her along the way. And inside each room these guys really gang up on her again and again with lots of anals and DPs. A very hot pursuit for this pretty, nice-ass lady this certainly was.

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