No reason to- unless you seem to be down on power- I have had several conversations with Dan @ Indy spec, and he see's allot more motors come in for a rebuild that didn't need.. He has seen motors go 5,000 miles and others go 500.
I can tell ya that mountain miles seem to be allot harder on the sled than trail miles.
We here at my shop don't tear into them Axys and the Pro's ( 13 and up) unless we diagnose an issue.