Friction and pressure are, well, friction and pressure... everything wears, and metal fatigues and eventually bends from repeated collisions.
How long it takes to fail and each person's own definition of what's considered excessive are really the questions; and there are too many additional factors to consider to come up with a definitive answer for all knives and situations.
How long it takes to fail and each person's own definition of what's considered excessive are really the questions; and there are too many additional factors to consider to come up with a definitive answer for all knives and situations.