I failed to mention this was a first time strategy. To see if I want to return. In repeat visits I always leave more than the donation stipulated. I usually book half hours, stay for anywhere from 30-45 minutes and pay for an hour.
BUT, only if the girls are more interested in me than their payment. I feel a SP should be able to make their clients feel that way. Even if they are simply play acting. Nothing worse than a visit where you don't feel particularly welcome or you just feel like your being rushed out the door. I have had many SP's who made me feel that way, never to return visit.