I don't care that much. Lol, it's not my web-site Becky. And, I'm not the one scraping the bottom of the barrel of CPM for clicks. W00T! You just made another 0.0000004 cents.
You never met gwb-trading? You don't hang in politics enough. Dude starts a new thread of copy/pasted spam every three minutes for hours at a time. It's 2025... open those eyes.
The down side, of course, is that if you're too restrictive w/ the CAPTCHA you risk turning the place into a baron wasteland (pun intended). As opposed to what it is now... a noisy wasteland.
Having an interactive chat is nice. So, rate limiting posts is probably enough IMHO. But, new threads? Signups and logins? Content quality might rise. Again, it's 2025. There are good ways to prevent the kind of canned crap that's getting through. Unless of course the cesspool thing works. Like I said, I don't care much... my bot doesn't fish for CPM clicks.
Percent of posts? Or users? IDK how much it matters... a/b test a CAPTCHA every 100 interactions and find out.