I have always been fascinated with the moment when it crosses from the outside world into the scene....for me the preliminary chat/negotiation (for which i understand the necessity) really delays that moment and so hampers the experience and the interaction from developing... i think the "slow build" can take place before the session if there are instructions for how to prepare, how to arrive, or what to do upon arrival...esp if the instructions are revealed late or in real time ...being talked in on the phone for instance or being told to arrive at a location at specific time and place and how to act upon arrival ...so the tension is there and then when the physical encounter begins, its already a heightened state and im ready to be taken "over the cliff"....