Indeed, a damaging UV dose is a damaging UV dose. If some of it is absorbed by melanin in the epidermis the damage is reduced but it is still more dangerous than not being exposed to the damaging dose.
Skin colour (tanning, =evidence of damage) is protective against melanoma risk because it reduce UVB exposure, though you have to be exposed in the first place. Melanoma risk is linked to periodic lobsterness, especially in the young, rather than cumulative exposure. But the aetiology isn't that clear...
Long-term exposure (as opposed to short-duration high intensity) tends to lead to a more UVA -biased exposure spectrum, which makes your skin leathery and prone to things like squamous cell carcinomas, usually much less of a problem than melanoma
You've got to be careful with suncream though - there's reasonable evidence that when its active components get, well, activated
, they are themselves carcinogenic. The best advice is no exposure; for audax that's not usually possible, so you could use an
opaque sunblock or you could moderate your exposure early-season and become leathery.