Replying to OP, yes if you see someone enough i feel you would always get something more than advertised. It might be more than whats 'at discretion'. Its hard to say for Escorts, but for masseurs, if you can get anything from them, then i feel it would definitely be just a select few.
I was seeing one masseurs on and off over a very long period of time and i asked for FS, but never got it until quite some time after (maybe after ~1 year), but i had to bring a johnny and she never had any and I had to take it away with me after.
Conversations had always end up with 'never' but never say never!