For every example there is a counter example... several years ago in the Rockies two hardmen were climbing Grand Central Couloir, the leader fell off the crux, stripped his gear and Factor-2ed on the anchor... both shitty screws pulled out of the belay as did one of the belayers two tools, the other tool held both climbers. After resetablishing the belay they finished the route. You can read the account in the CAJ.