When does normal wear become a durability issue?

Not every scratch, softened click, or finish change is a durability failure. What matters is whether wear appears unusually early, progresses in a way that affects use, or indicates a weak point compared with normal handling.

I like to document visible changes first and make the stronger durability conclusion only when the pattern supports it.

That avoids the two extremes: pretending cosmetic wear never matters, or treating every mark as a defect.

The timeline is important too. The same change after three days and after six months do not mean the same thing.

Exactly. Duration and use conditions belong next to the observation.