As a Bull, this is often how my encounters go with wives/gf. They are eager to experience anal with a large cock, but often cannot hold out until I cum, which depending on her age, looks, verbal or not or if her asshole really smells good, could be from 2 minutes to as much as an hour. Safe words work best because most will be crying in discomfort and abandon, so it doesn't pay to be sensitive, only listen for the safe word.