In the analogy, though, I do know people have a hard time distinguishing between pain and soreness. Such that it is not uncommon for people to exercise too hard and trigger pain, which will slow them down. As such, I expect that sun exposure is likely the same. I even agree that it is probably easier to jump over any threshold that there may be and to get too much sun. I have a hard time thinking any darkening of skin is a sign of damage, though.
I also think it is tough to distinguish between damage versus wear. Which, is probably just my not liking the language of "damage" here. Do we say that guitar players have damaged their skin to build calloused finger tips? (Genuine question.)