I recently replaced a pair of praxis rings at barely 10.000 mi. The little one was optically worn but worked OK. The big one may have have had some more miles in it, but a pair of fresh 5 arm Shimano rings, that is also forged, was cheap enough to warrant early replacement. I believe forging is far superior to milling and turning. Cheaper in large volume and last longer. Sadly steel rings are not common.