but the passage of time in between asking and having seen the provider from whom you are requesting the reference.

Somewhere around 2 to 3 months seems to be the cutoff in most cases.

If you have a regular whom you see on a fairly frequent basis, I would think she'd have to problem refering you to any number of providers, though I would hope that some providers will chime in if this is not the case.

I know that I have done this with my regulars and never had any negative comments regarding this.

It is very important and good manners to always notify the provider a head of time that you intend to name her as a reference so that she expects and is not blind-sided by the request.  If she has any problem, she'll then be able to tell you so.

I am a newbie , have met and seen a few well known ladies and they have obliged me with their references numerous times ( 3-4). I like variety and have never met same lady twice in spite of stellar encounters. I do rotate references and have signed up for date check as well. Some newer ladies still look for references beyond date check. My question is how many times( to be sensible) can I bother my old references without pissing them off?

Have them offer a referral on TER, which is a permanent sort of referral other providers can see.

constantly seeing new women, you should constantly have new references to give. I don't mind giving references but 3-4 is the max times I want to give a reference for someone I've met once. If you're a regular, that's different.