Burnie5204
Agree
Windmill unbalanced-in-flight is the limiting situation, although I suspected that the OP was talking about what he saw on-the-ground.
In flight it is regulated to remain within safe damage tolerance limits (as you said). While on-the-ground it's an economic thing if any thing begins to collect detectable wear (fan-blade bumpers. dampers, etc.).
I suspect that most who read these posts will think that higher air speeds mean more wear. Not true in most cases for the fan blades that hang loose in their slots when assembled or for bearings which depend on pressure balancing of their aerodynamic thrust load.