Its just biology, does not matter what gender or orientation you are. Sometimes you just feel it hit, and you go go go. Every once in a while, I will go 3 time in one day, Wife, Dog, Wife again, or any number of combinations. It can be caused by a whole slew of things, changes in nutrition, changes in hydration, etc... Your libido will spike, and bang, is all you want to do. Things like low moods, depression, etc, can also pull it downward, and then when you get past those types of things, all the sudden it will kick in again and wham.
One time I had it hit really hard, and for 3-4 days i was pounding any partner who was willing, the Wife actually shooed me away once or twice because she was tired, XD