Ever had a wheel bearing failure? You get that metal on metal knocking from the back wheel, and it kinda ruins your day, right..
Seeing as I’ve had a number of ruined days, these days I consider wheel bearings as a consumable, a service item, and change them regularly. On my enduro bikes I generally change them every year, or 50hrs, whichever comes first.
This is what this bikes bearings looked like after only 2 years of neglect: