This is probably different for everyone. I never watched the clock closely. Some times my sessions would run over the allotted time. Some times, we may end up finishing a few minutes early. I always went with the chemistry that was taking place and let the energy in the room be the guide. No one ever said anything to me about it. But, looking back, I can see where it may bother someone. What would you suggest when the session was been great but it was time to end it even if there are a few minutes left? A good femdom sessions always reminded me of a good gym work out with a private trainer. As wonderful as it was...there is a point where it is done and to drag it on for the sake of the clock just seems to take away from the overall experience.