I would have to say, try it out, you will love it. The first time I did, I was as apprehensive as you are but let me tell you, once you've done it once, you will want to do it again and again, budget permitting, of course
I initially booked the half hour, but when we were done, I politely asked if I could come back in a couple of hours. She laughed and said of course. I think I had to wait 2½ hours, though because she was already booked for the time I asked for initially
Actually, I did that with her but not back-to-back. I let a couple of hours lapse before I saw her again. I'm not in my 30's anymore so I need time for my stamina to build for the 2nd round. LOL