I`ve seen the inside of engines using the OLM change interval (lots of sludge and buildup. can`t say anything on the inside of engines that people take care of with more frequent oil changes because we never see any type of failures, even lees oil leaks.
As I`ve said before, the OLM is only a way to make a car look more appealing because it appears it needs to be maintained less. I`ve seen Mercedes cars with 60k miles with failed timing chains running the 12-15k mile interval. guess what Mercedes told the customer, pound sand! the same cars with a 5k mile interval have no failures.