The 300 to 500 mile rule gets repeated everywhere, but it ignores how differently shoes wear depending on running surface, body weight, and gait. I’ve had a pair last 550 miles on soft trail with no issues, and another pair go noticeably dead by 280 miles on pavement.
A better test: press a thumb into the midsole foam. If it springs back slowly instead of quickly, or if you can feel the ground through the heel more than you used to, that’s the real signal, not the odometer number on your running app.
I now check the thumb test monthly instead of counting miles, and it’s caught a dead pair of shoes twice before the mileage counter would have.