Two hours is good to drink and have fun. I like 2 or 3 hours.

In two hours I expect 3 times sex and in 3 hours 3 or 4. Depends on girl as sometimes I like to talk more.  

2 hours though base case is 3x cumming for me.

Honest opinion

Discuss it with the lady beforehand so she can be aware of your desires and you can be aware of if she’s okay with it.  

I don’t give a fuck if dudes here think I’m a “white knight” or whatever, there’s too many entitled “mongers” (I hate that fucking term) that think because they are paying for a woman’s company that they are entitled to whatever they want (and OP, I’m not referring to you specifically; I’m making a point).  

Let’s be real: how many dudes here think that they’re so hot and good looking that the women they see are soaking wet for the entire duration of the appointment and are okay with physical activity without getting tired or sore?

Paying for a multi hour appointment is not akin to an “all you can eat” buffet.  

Having said that, your expectation of 50% is reasonable, I would think. One needs to factor in shower times (if one hasn’t showered and groom oneself before an appointment, Jesus) before and after.  

Again, discuss it with the lady you’re looking to book so there are no unreasonable expectations.