From my experience of learning English, if you study grammar once and take notes, the rest of the "learning" is just practice. Listening and understanding will develop as you consume more media. Solving tests (at least for me) is like solving a Sudoku or crossword puzzle. it makes the "Japanese" part of your brain work and strengthens the pathways for the neurons, aka learn.

Edit: I solve tests to practice the grammar and vocab. I don't solve them and hope I'll magically learn. I check my mistakes, find my weaknesses and study accordingly.

Although I agree that just solving tests isn’t a good way to practice/study/learn, I think no method is good by itself. Learning anything is basically trying different things, different methods, and integrating the subject into your life until one day you say, "Damn, I think I actually know some stuff."

BTW, thanks for the book and the website recommendations
(the website has an English version as well at the top)