Curious for thoughts from fellow hobbyists on when ads or reviews have become too old to be worth bothering with. If a recent review has been posted, but the most recent ad is a few months old, do you bother trying to make contact, and if so do you send screening info requested on her website or first wait for a response?
If there's someone you want to see, why wouldn't you at least inquire if they're still around? A lot of girls just don't advertise very often.
Well I'm not a hobbyist but I am still going to respond 
Your best bet would be to email the provider and ask her if she is still seeing clients. I wouldn't send the full gamut of screening info if you're doubting whether or not she is still actively seeing clients because you don't want to have your information just sitting in someone's unmaintained inbox, not knowing if it's going to be disposed of anytime soon (and what if she's inactive because her ability to do business has been compromised by LE?)
I think review length of time is pretty arbitrary- the vast majority of clients from TER do not post them/contribute to the review community. It's easy for months to go by without a provider having a new review.
Some providers don't actively advertise all the time, seeing as advertising can get time consuming and pretty expensive. Even though there is no expense in posting ads on TER, she may just not want to take the time to post an ad.
some fly as well
A few months between reviews is not unusual at all for low-volume and UTR providers, or providers who actively discourage reviews.
I have a friend who rarely advertises but has a bunch of regulars that gives her the volume she wants. And, come to think of it, it's been literally months since I've paid for an ad, because of other things going on in my life. But I'm still active and seeing clients, including new clients.