Lord don't I know, I've helped a few people learn to file chains. One of them was a firewood cutter that actually sold firewood, another was a tree farm owner that had the tree farm for 30 years. 30 years of cutting trees and he had never learned how to sharpen a chain.
I spent an hour and half sharpening, helping and explaining how to sharpen a chain with one bloke. Then 6 weeks later he showed up and wanted another 'lesson'. The jerk just wanted me to sharpen his chain again. I told him I already showed him, he replied "I forgot". Sorry about that, you should have taken notes...