I have been trying between 1 hour and 30 min for a while, but ended up settling with the 45 min booking. I believe is the best balance, 30 min is too short either to see if the WL and I click or to really enjoy it if we do click. 1 hour its just a waste if we don't click and I always end up leaving before the 60 mim mark.

If I'm having a great session than extending over the 45 min is usually an option, only have running into trouble once when she had already another booking.