Disclaimer: I read the CryptoNote white paper in detail, know a little of the math, but had not previously studied ring signatures nor have I yet looked closely enough at XMR's implementation.

Having said that, I grok that every XMR transaction clubs a number of possible addresses into an ad-hoc ring, one of which will have been the actual message participant. I can see how this obfuscates the payer/payee.

But... what about recurrent transactions? If Alice sends 10 XMR to Bob on the first of every month, even if on average dozens of addresses are mixed, within a few months it will be clear to Charlie who it is that is sending the XMR to Bob. And the more addresses we include in the ring, the fewer transactions will allow us to notice that only one of them is a recurring transactor with Bob.

I know I'm missing something obvious, and "Jeez buddy, read (this link) before asking next time!" is a much-appreciated answer (if it includes a relevant link)

Thank you!