Only if I think I overrated or underrated by my more than .2
Only if my original rating was one of my first ratings when I was stupid
Only if my original rating was quite a while ago
When I have an IPA fresh which I first rated stale
All the time
Only if I want to increase my original
Only after seeing 2pac’s rating of the beer in question
I’ve heard a bunch of different thoughts on this. Me I’ll definitely change my ratings, especially since I feel that beer has gotten better and many old school whales don’t live up to modern standards (Looking at you, Dark Lord).
I change it when I shat on a beer and it was clearly not in good condition and I have it again and it is in a different state. I don’t tend to rerate excessively high rates, as those offer a good historical reference for me.
I’ll always compare my rating to see if it matches, but I’ll only change it if there is a definite variation from my past rating (or just tweak my old rating if I notice something new). However I add additonal ratings for beers known for having year to year differences (Dark Lord, KBS etc).