I've got two sets of wheels, and I rotate my tires every oil change, so it's not laziness that's the motivation. Instead, it was that with 2 sets of tires after 7 years of driving both sets still had tons of tread left but were starting to dry rot. I put about 60k miles on the car during those 7 years. So if I can get ~30k miles out of a single set of snows, and use them up within 5 years, that would be a much better use of resources. The cost isn't really a factor either, I just hate wasting stuff.

I've currently got something like 15k mi on the tires and 2.5yr of year round use. They appear to be wearing evenly and normally.