I think you have to play some thing as described here on a case by case basis. I don't think you can have a standard rule. I think it boils down to communication between client and provider on what is acceptable especially if you see each other on a regular basis. For example, I see one girl often and at times she wants to be UTR and at times she wants the reviews or word of mouth. Everyone just needs to talk about it in advance.
Also, for the life of me, how can a provider "claim" exclusivity" over a client? That is kinda counter intuitive of the hobby. Providers see dozens of men if not more in their career. As a client, I like seeing a variety of women. Now, I do rotate around seeing a core group of ladies, but they all know that I play the field and may go a couple of months before seeing them again. I get that some girls see a client as a cash machine and "count" on him to see them in order to pay the bills. If a girl finds herself in this situation, she needs to stop providing and find a sugar daddy.