Mine go together @ 9am and it takes until about 11:30. Usually i stay to chit chat while she does Loki and then to help hold Sammy. Sometimes I leave while she cuts Loki but come back to help with Sammy. She does one dog (or one family) at a time.
We used to take Loki to a place that kept him for 5 hours and he would shake and freak out when we dropped him off. Now he runs up to the door to give our groomer a hug.