kinda depends on the girls for me. with my wife, we usually go around 25min, but that is because that is about all she can handle before it is too much for her and she asks me to cum. she will have cum several times byu then anyways. with other girls, they can handle longer so i go longer. i think if it were just up to me and not pacing to meet a girl's desires, either shorter or longer, i would probably go around 45 min