My worldbuilding brain won't turn off:
So all full service sex work is legal and legitimized, it'd be horribly hypocritical to have publicly funded male sex work that is admired by all, and to simultaneously criminalize and demean other sex work. So that's only happened historically in particularly regressive regimes.
It's actually been more common for the opposite to happen: societies that considered it a civic duty. More than a few ferrety countries have required men to go into military service for a year or two, unless they were serving the public in some other way: working as a firefighter, doctor/nurse, or a sex worker.
Thankfully that's not the case any longer. Now the job is more of a professional/volunteer thing, rather than a conscripted force.
The majority of the workers are professionals: they went to school for this, this is their only job, they're paid by their city's tax budget. They work year round.
But there's also a volunteer contingent, something like the Army Reserve? They've got the training (and their certifications are up to date) but they have another job (or they're in education or are a homekeeper or whatever). They're only called in for big surges.
See, heats are a hormone level thing but they're environmentally triggered. In "nature", they'd trigger every spring after maturity*, so basically all the ferret girls would go into heat at once.
But in the modern world, that's less the case. When ferrets go into heat can happen at different times, and then it tends to be yearly around that time. It's shifted all over the place thanks to the modern world messing with environmental triggers: artificial light, global warming, air conditioning... It mostly stops the natural triggers from working so it's just anytime.
But... Enough ferret girls DO go into heat at the usual time that there's always a big surge around the beginning of spring. The professional crew can't keep up at those times, so they call in the volunteers. It's a civic duty, a bit like jury duty? You can't get arrested or fined for saying no, but many people do it just out of a sense of civic pride. In big cities though the surge is often bad enough that they do offer more than the basic compensation. And there's protective laws for doing it: your job can't fire you because you had to take a week off to rail ferretgirls into the mattress.
You gotta have a certification though. It's not that hard to get, a few weeks of classes and a hands-on test at the end. All universities offer it, and usually you can find a community center offering classes in an old church. You just gotta take lessons in how to do it properly, how to be polite and appropriate, what you might be asked to do, and the hazards** of the job. Then you go down to your local DHM*** office and take the in-person test. Certificates are good for 5 years, then you just need to retake a paper test and the in-person again.
But yeah. Most of the year it's just the year-round professionals manning the shop. How many depends on the population. Your small towns will just have a single station, and big downs are divided into a bunch of districts. Universities usually have one or two stationed on-site.
* thankfully the ferret population doesn't have an issue with precious puberty, that's all I can say. All ferrets going into heat are at least the ferret equivalent of 18.
** and they are many. This is a job and a medical thing needed to save a life, but ferrets are still human like you and me: it's very hard to completely avoid catching any feels. And God forbid you are being called out to save a ferret woman because her husband isn't up to it: they have policies about this exact situation because of all the murders.
*** Department of Heat Management, the government agency that oversees this profession. It's an eternal source of humor how they're stereotyped as being the "sexiest government agency" but really they mostly do paperwork and run it all like the DMV so it's about the least sexy thing imaginable, even if sometimes you gotta go down to their offices and fuck a gal hard enough to prove you can do it****. Thus the humor: that dissonance. Plenty of sex, but no sexy.
**** the existence of the certification must come up in dating/cruising, and that's gonna have some interesting implications. Imagine you're going out with a guy (or a gal! It's the 90s!), and they pull an official card from the government that certifies they know how to Fuck Good and they've had to prove it. There's plenty of bars where you can get laid on the strength of that alone.