It varies for me
My record so to speak is 3.5 hours with two cums but that isn't the norm as both parties tend to get bored before that.
Normally it will be 20-40 minutes, once she has come a few times I will flip her over and bang her hard to make me come.
Now if a girl gets vocal as she comes that will make me pop straight away, don't know why.
I do find if I get past the initial omg sensation then I can controll it well
