I can attest to this practice. Quite a few years back, I asked Sue about the tip, and what it should be. She gave me guidance, the “normal tip”, but also said something that really stuck with me, that I practice to this day. Think about what you would pay for a wonderful time, if everything was exactly how you wanted it. If you do that knowingly, and pay that amount up front, you set the tone, and most of the time you will have a great session. (Thank you Sue).