A very long time, definitely worth it. When my gun wasn't ejecting, it was cramming empty cases back into the feed lips and spread them a little. Per Hilton Yam = 10-8, it's time to throw them away when they spread...I bent them back in with a little desktop vise to see what would happen and they have held up fine.
I trust mine on my nightstand now...no bobbles except when I try to feed a badly goofed reload.