Burn through may have been the wrong choice of words. I do adjust my Kirbys to the right height, however, if you have a thicker carpet even correctly adjusted nozzles will strain the belt.
I credit it alot on the Omega to the larger brush roll the belt has to pull to begin with. I didn't have the problem with my Tradition, and never a problem with the UG.
Since using the new belts which are also used on all the power take off attachments, Miricle Head, Rug Renovator, and Handi-Butler. The newer belts are just built better.
When you will see burning is when you use an off brand belt. It may work for you for a bit, but it will not last like a genuine Kirby belt.
Beware of "Made to Fit" when you buy. The name Kirby will be stamped on a genuine part.