Strava tells me "experts recommend" replacing shoes at 300-500 miles. I've got about 6 pair of the same running shoes that I rotate through. I can definitely say the cushioning wears down at some point, but haven't retired enough shoes to say for sure when. Over 500 miles for me, typically, though sometimes I notice a pair I haven't worn in awhile bugs me, then forget about it. Then they turn into gym shoes, or carwash shoes, or...
