I have never gotten 400 miles out of a shoe. I'm 190lb runner and have gotten as low as around 200 miles and looking back through my Garmin retired shoes managed 370 once. At any rate, shout out to these Brooks Ghost 13's :)
Normally something (knees) let me know it's time to switch. These I retired due to running out of sole! At any rate, 95 activities, and 444 miles is a record for me!
To me, it seems like around the 300 mile mark, the shoes are still usable but less forgiving. For example I might start experiencing pain in my right toe with older shoes, but it's my fault for running funny. I've gotten 6-700 miles out of shoes before at 190lb, and now I've just stopped tracking mileage on them. Mostly I switch them out when I'm afraid they will break or fall apart somehow mid-run.
I'd have no rubber left on the bottom!