Worn Drive Belts

I own a 1996 Murray Riding Mower, 8hp, 30" cut.  It has served me well for many years. Finding original parts is getting tougher. Within the last year I have had to replace two drive or motion belts. The belts used were supposedly substitute parts for Murray's drive belt, P/N 037X65MA. I have looked at both the engine and transaxle pulleys and did not see any sharp burrs that might be shredding the belts.
I am beginning to think these alternate parts being manufactured oversees with inferior quality.
 
Anyone having the same problem or have any other reason why these belts are being worn out so quickly? I only use the mower 0nce a week!

Thank you for that information. Changing that drive belt on a Murray Rider is difficult and a tedious process. I have change numerous belts over the years and as I get older it gets tougher. Also, because the engine and transaxle are so tightly packed to a small chassis, one has very limited observation of the drive belt, engine and transaxle pulleys.

Whenever I replace that drive belt, the first thing I do is remove the mower deck, jack up the rear, put jack stands underneath, remove the rear tires, remove the rear bracket supporting the transaxle and finally remove the bolts holding the transaxle and lower it. It’s labor intense, but it gives the best visibility and makes replacing the belt easier.

I gather you checked the two idlers and any brackets that move to keep proper tension?
 
https://jackssmallengines.com/jacks-parts-lookup/manufacturer/murray/1996-models/lawn-garden/riders/lawn-tractors/46-cut/46901x92b-lawn-tractor-1996/motion-drive 
 

I am having trouble uploading 2 pictures of the belt I removed. There is extensive damage to this belt that’s been in for less than a year. Plus, the mower has been idle during the winter month.