It makes sense; if you like to give and receive head - and I do as well, the 69 is the position to go with and it kinda avoids that problem with busting a nut and now you'd rather go pave your driveway on the hottest day of the year than to keep having sex. Sure, it could still happen but you're both sharing the moment. Having someone sucking on your cock as they're busting a nut can be... incredible. I know if my 69 partner makes me cum, his dick is gonna catch a bad break as I continue to suck on it and, yeah, hoping that he's gonna cum any second now.