The thirty minute period is the industry standard. That said, spas in Mississauga and Brampton offer forty minute sessions for maybe ten dollars more on the house fee, and without any extra in-room charges. This is a good deal, bearing in mind that if a spa is not busy when you are there, many girls will let the appointments run longer anyways, without an extra charge to the house. When longer appointments increase the in-room costs, as they tend to in Toronto, then no, it's not good business for the client. Better to go with the standard half hour. On the other hand, with an SP I have never booked less than the full hour. This is just the way I do things.