There's nothing like running long trains to weed out all your rolling stock that have couple problems.
After getting my fourth loco set up on RailPro, I MU'ed my fleet together and put the vast majority of my rolling stock behind it. Granted, when you're only talking 24 cars, it may not seem like much, but when you add in a 3% grade, you find out really quickly which cars have a couple that is mounted too high or too low or is, you know, plastic.