If this "outdoor Exposure" is such a problem,
and it seems according to the supplied chart that deterioration is fairly linear,
and it seems most here do not have much, if any "outdoor exposure",
and those same people feel a 2 year life cycle in their own case is therefore foolish,

Why not incorporate a tattletale UV exposure color changing thread/strip/indicator? into the belt and make it a simple pass/fail, and no longer time based?

I'm sure the technology exists.

Oh I forgot, no money to be made.

Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.