I believe every six months is the standard interval, but IME the pain relief lasted much longer (years for the first time, and a year and counting for this most recent round). I am all about buying time, because I have done quite enough major ankle surgery, thank you, and I’m not convinced the results of another arthroscopy would be much better in the long term.
My ortho has lately been starting to hint that I should consider a joint fusion (because I am too young for an ankle replacement, and they are not fabulous or long-lasting anyway), but I told him that my plan is to continue to buy time until science comes up with a less sucky alternative, or until I really can’t walk, whichever comes first. I am hoping for stem cell-regenerated cartilage. Researchers, get cracking!
(My ortho grudgingly agrees this is a reasonable approach, especially after I explained that my grandmother had a knee replacement in her 70s - she is now 97 and has outlived it.)