I have a lot of experience with Gen 2 belts and as mentioned environmental factors play a large factor . There is now a cleaning product which can be used on belts ( i do all of mine annually) which helps keep them in good condition ,plus have all of mine on pulse units and inspect the coating regularly . The biggest issue i have found is if after installing the CSB's and running you need to make sure there are no foreign objects / builders debris etc... Around the Shivs that can damage the belt during running . Sounds obvious right ? I inherited a few units less than a year old that i had to change the belts because they were damaged from handover. However i also have some units 10 or 12 years old and the belts are like new .