The 1/4-20 threads that go into the body of the camera are under a lot of stress, and every time you mount an adapter or a battery grip, it wears on them. they aren't very deep, so the wear and stress are acting on a small amount of metal. All that said, I don,t worry about it as long as I know everything is in order and the quick release is set right. If you want to worry about metal fatigue and breaking bolts, don't drive a car, especially around other cars. Ther is a lot more than your camera riding on the quality of lesser bolt/thread mechanisms than the camera mount set up. I throw the tripod over my shoulder and move, I set the thing up in a boat and slam through chop that makes my knees ache at the end of the day. I am more worried about the lens mount than the tripod camera interface. 25 years and no worries.