of 3-4 women that I see regularly. "Regularly" for me is 2-4 times per month. I usually have a CF that I see more than the other regulars, often twice a week for a month or two. In addition, to keep things fresh, I see one new girl each week. Sometimes, if I really like a new one, I will repeat and may even add her to the regulars group. The exception is Las Vegas, because many times the girls are only visiting for a few weeks and are not there the next month when I go. I also have a group of touring girls that I see sporadically based on when they are in SoCal. This is the long-term group, some going back four years. The longer I see a particular provider, our relationship evolves into one of friends with benefits, with one of the benefits being a donation for her, and time off tee clock for social outings for me. It takes on a completely different style than a normal provider/customer relationship as the friendship develops.
So to answer your question, I would say the ratio to of new to repeats is about 50/50 in terms of number of providers, but since I usually book more than an hour with my regulars, the ratio of new to repeats in terms of hobby hours would be about 20/80.
When I decide to repeat, it is because there was a good connection with the provider. It has little to do with skills and more to do with playfulness and personality. If skills are weak, I can always teach them, but if personality is lacking, there is nothing I can do to make it more fun.
I mainly try new girls because of attrition. I see mostly Asian girls, and many don't stay in one city too long, so I like to have replacements in the wings to pick from when a regular goes to another city or back to their home country.