I do not believe that high / low range are speed specific other than the low range RPM's will limit your speed by design and your tolerance for increased engine noise. Although I drive a Uforce you may find that the recommendation in the owners manual applies pretty much across all platforms. No mention of increased belt wear. My previous ride was a 2002 Yamaha Grizzly CVT that I had for 15 years and never wore out the belt driving mostly in high gear.
L Range
This position selects the low speed range of
the gearbox. It allows the vehicle to move
slowly with maximum torque at the wheels
CAUTION
Use the low speed range to pull a trailer,
carry heavy cargo, go over obstacles or
drive uphill and downhill.
High Range
This position selects the high speed range
of the gearbox. It is the normal driving speed
range. It allows the vehicle to reach its maximum
speed.