Well, in my opinion these courses covers the basic modelling and the basic processes of the variant configuration. If you already understand all possible processes and Scenarios the variant configuration offers, the you might be right about "a waste of time".
However, when you don't understand all scenarios and processes these courses might give you some fresh ideas, how you should model your own products and processes. In that case the courses wouldn't be "a waste of time".
I have no clue about your knowledge about the variant configuration in SAP, but if all your knowledge is gained from reading in a forum and experiments in your own system, I think it would be wise to give these courses a chance. Why not just try the first course?