Yes NessNess, this is where I was going with that question. Because the problem isn't that years are not countable, but the singular form of the noun makes counting it awkward. I think context around a singular noun is important. As used on this forum, one less year means we started with a finite number larger than one and have subtracted from it, thus, "I can work one less year than the 15 years on which I had planned." In this context I think year is countable as part of an equation. You know, like those pesky word math problems.
Not to belabor the point for the grammarians, but language evolves (and debates like this one with the logic behind it are part of how that happens) and there are formal and casual uses of language. But yes, technically, formally OLY is incorrect. But OLY is casual speak and here to stay.
Sorry OP, I know you weren't intending to open a can of worms, but you know how this forum likes to dissect and discuss.