It is such a simple technique, that makes such a huge impact on ones writing, and yet no teacher bothered to teach it. I spent all my school years writing monotonous essays of five-word sentences. Week after week I would make another one, and I could clearly see for myself that they were bad, I just couldn't tell why. So when I asked my teachers for help, asking "what is wrong with my writing?", "what am I missing?", all I ever got back was a bad grade and the same useless tip: "just read more".
They might just as well have said to "draw the rest of the fucking owl."