How many miles do you go between belt changes on your vehicles? I could change mine at every oil change and call it a precaution but that would be just plain wasteful.
Anyway, when they use the design of slipping the belt so they can call it a "variable speed self propelled" so they can have another model in the lineup to sell at a "cheaper" price point but at the expense of a part that needs to be replaced every couple years from "normal" use, then yes, it is poor design (at least from a consumer point of view). It benefits the manufacturer by creating a consumable part and the dealers who then provide service to those who aren't mechanically inclined. I would change the belt myself but my time is also worth something to me so I would rather spend an extra $100 on a mower with a better designed drive system. Sorry, at $600 for a "premium" category mower, it shouldn't need anything other than fuel, oil changes, blade sharpening, and minor lubrication for at least the first 5 years of homeowner use.
My father still runs his 3 speed rear wheel drive Toro Recycler mower he bought in the early 1980's. Still runs well and still uses the original drive belt. The rear wheels even have half their tread still on them. Only had annual oil changes and blade sharpening. Still mowing the same 1/2 acre of grass it has always mowed. Point being that a superior design will last and shouldn't require "consumable" parts every couple years.
