I have graded for fourteen years: two features, a lot of commercials, and more music videos than I can remember. For most of that time I learned the way everyone did, by sitting next to people who would not explain anything.
So the courses explain everything. They are the whole job in order, recorded in my room on real projects, with the mistakes left in because the mistakes are where you learn what the tool is for.
Every course is one purchase. You keep it, you get the updates, and if it is not for you I refund it. That is the whole deal.
A calibrated monitor, a grading panel, a camera that is usually pointed at me. Nothing you cannot build yourself over a year or two, which is the point of the studio-setup course.