I was looking to find a provider that I can see on a routine basis (maybe 1 or 2 times a week).  Should I expect to be able to obtain a reduced rate if I am seeing her often?  How often would be necessary and what would that rate reduction look like?  Or should I look at the rate as being non-negotiable?  If the latter, then I would rater see a variety.

i'm not sure why you are so enamored with the idea of getting a provider to lower her rates for you, but all you're doing is being cheap. clearly it's not an issue of budget since by your own admission you'll just see a variety if you can't get a discount from an individual provider, so it must be some kind of attempt at a power play.

if you really want a discount, you need to start thinking about what you'd be willing to give up on your end to make it worth her while (and no, once or twice a week isn't making it worth her while). somehow i doubt you'd be willing to accept less than 100% of a session, so why should a provider accept less than 100% of her rate?

Predictability, reliability,  as a reward for loyalty, because she doesn't have to worry about safety, because time is money and seeing good repeat clients saves her time and therefore money, and because it is just good business.  Do you have a loyalty card anywhere?

.... offer a reduced rate for frequent visits if you prepay. Otherwise it's probably best  if you wait for the lady  to offer it to you.

END OF MESSAGE

I can think of many reasons why a frequent flyer discount is beneficial to both parties.  
For the provider, if it's someone they would like to see on a repeat basis, I could make sense, you don't have to deal with an unknown quantity or screening or getting to know someone. I imagine to some people the lack of hassle is worth some amount of discount. It's also a way to show your valued clients appreciation.  I imagine a small discount probably could lead to more income in the long run due to increased bookings. And guaranteed income is sometimes better than potential income.  
All of this assumes that you actually want to spend multiple sessions with this person, and I would not ask about this from the beginning. If you don't then this doesn't make sense.  

I guess I'm operating under the assumption that spending with hobbyists isn't a uniform experience and that some providers don't see every minute as something that has to have maximum dollar value associated with it.  
In my line of work I do things that don't bring me maximum value at the time because I think it's better for business in the long run, and will generate some loyalty. Or because I like the person. I assumed the hobby wasn't different.  
Again, everyone can do it how they like and run their business how they like and I think you're a jerk if you demand or expect this. But I don't think it's beyond the pale to ask about it on a message board.  

Everyone likes to say "this is a business."  In literally every other business I have interacted with if I walked in and said, "I would like to commit to multiple business interactions with you over a long period of time in advance," I'd ask for a discount of some type.  Literally every time. And the fact that we shame this guy for even suggesting it means maybe it isn't as fully a business as people make it out to be.

QUALITY along with QUANTITY which includes what they refer to as a "Grandfather rate".  That simply means that after a few weeks of reciprocated adoration and flexibility timewise, you should both be able to figure out a suitable in-between cost for a good time had by all

I know from experience that it is best to have someone that knows your body and you know theirs; then, what's a couple of bucks?  Especially, when it's frequent.

Personally, I only know one girl in DC who could fit your bill and her name is Chloe Carter.  She is top notch and I love her!

XXX-Giselle Parker

Q: Should I expect to be able to obtain a reduced rate if I am seeing her often?
A: No.  Would you expect a reduced rate for a plumber that came to your house often?

Q: How often would be necessary and what would that rate reduction look like?
A: See Q&A for number 1.

Q: Should I look at the rate as being non-negotiable? If the latter, then I would rather see a variety.
A: Yes

Comment: "then I would rather see a variety."
A: as is your prerogative.