I wouldn't worry too much about cleaning belts or breaking them in,although it doesn't hurt, especially if you are having belt issues....it's an easy way to eliminate that as a factor.
Another thing that will junk a belt quickly is any water or snow getting in there.....seal up the area and don't use vents without flow rite material in the clutch area.
Alignment has to be close,but even if it's a little off you shouldn't blow belts quickly. Deflection should be as tight as possible without squeeling or creeping.
Setup/calibration is probably the most important factor. You should see 8200ish rpm at full throttle.....if its much more or less, it will make a lot more heat and shorten belt life dramatically. There's a lot more to clutch calibration, but with the stock prormk calibration, simply adjust arm weight for your altitude and it should work good and belts should last.
That being said, the clutch temps on our 12 163 pro RMK are every bit as hot as any Doo TRA setup I have ever seen.....which is surprising to me as the p-85 has historically run cooler. But no belt issues yet, it got a good test the last couple days in waist deep in BC
