With one particular fuckbud, our normal routine includes 2+ hours of fucking. He is an incredibly robust bottom which has given me the opportunity to significantly improve my topping skills by experimenting with a variety of positions and techniques. As you might imagine, we are both a sweaty exhausted mess at the end of it all.
With these marathon fuck sessions, I've noticed a definite change at around the 30 minute mark. Early in our fucking, it would be very easy for me to cum but I deliberately hold back. After about 30 minutes of thrusting, my dick starts to get a little numb from all the friction and it actually becomes more difficult for me to cum at that point. When my bud's ass is finally worn out, I will typically withdraw and jack myself to orgasm and then reinsert right before I shoot.