Part has to do with the teacher’s personal bent. I had one who was very much into the “Man’s Inhumanity to Man” and always focused on that theme, even though there were many others to be found in the "required literature. Plus when you are already depressed about things, having a depressing reading list is not good. I enjoy Kippling, Clancy, Heinlin, Schmitts, Twain, L’Amour and Cussler for my leisure.
I still have and use one, it works even when the electricity goes out.