This is true, but I don't think the Sequences need to teach what has already been covered to a sufficient degree of detail in the text. I can, for instance, vouch that Occlumency is taught well enough by the fic alone; since I read chapter 27, no-one has been able to read my mind! And I think I got the theory for conjuring a Patronous v2.0 down, too; as soon as I get a magic wand, I can put that to the test and see if it works.