What no one has mentioned directly is a general practice bit that may relate here. Many of us tend to spend more time in the shed working on what we sound good at, rather than what we don't. So enjoy the parts of a book like Arbans by wailing through what you can. That really rewards continuation. But spend more time each day on what you cannot do well. Try the stuff that seems within reach (perhaps not the "darkest" pages as said above). Also, as said above, Arbans is not really a methods book. Go elsewhere for the overall development plan and use Arbans as a filler.