I haven't done the National Camera Repair Course, but I did go through the entire National Camera Repair Guide for the Pentax K1000. These are different than service manuals. They assume you are a beginner and take you through every aspect of the camera; metering system, focusing, shutter speed control, winding mechanism etc. For me, this was more practical and helpful than learning about all of the different components of a camera separately. From here I can comfortably branch out to other Pentax SLRs and eventually work my way to other brands if I get bored.
In my opinion, the Repair Course is too broad for most hobbyists, even ones that are willing to dive deep. I think the Repair Guides are a better balance between valuable instruction and still doing something that's fun.