The difference is that on a 30 minute punt there's a strong chance I'll wish I'd paid for an hour, when I'm rushing at the end. By contrast, on a one hour appointment there's a strong chance I'll wish I'd just booked 30 minutes when I've blown my load after 20 and won't be able to cum again.
I said it before but I wish that parlour girls would offer pro-rata per-minute rates and let me pay as I go. In the sort of parlours where you just turn up and choose a girl without booking in advance. The rate would be, let's say £2 per minute. Since I'm only paying for the time I need, the girl is encouraged to give good service throughout, in order to keep me interested so I'll stay longer.
Think about how it works at a typically strip club with private dances. You don't hand the girl you've just selected a wad of cash for her to lapdance on you for 30 minutes! You agree an amount for one song. If she's any good you might ask her to stay and dance to the next song, for which payment is agreed. The alternative, paying for a whole load of songs upfront would be a disaster - lacklustre performances would be most likely. Much like how many prossies conduct themselves after receiving all the cash at once.