The key here is physical stamina and rest. I say this because I've suffered from this before, where I work a hard week and don't have time for exercise. By the end of the evening, I had enough energy for one round and that was it because I was just too doggone tired.

When I was younger and before kids, I slept in later and had time to exercise more. As such, I could go 4X/night and we'd both be happy.

Now I know that if I do not exercise and am not well-rested I will probably only last 1X, especially if we wait until 10 or later to get frisky. Sometimes SHE is too tired after 1 orgasm! So this goes both ways, IMO.

Most times, we go 2X with me giving her oral in between my orgasms as my cock recharges. After I cum, I tend to be more patient and focus on her needs.