I'm sorry, but I don't think you have much experience in learning. In this way you will only remember a fraction compared to focusing step by step on the different topics and purposefully recall all the concepts, ideally putting them to practice starting from scratch without looking at all at the book. Source: pretty much every research about learning agrees that the conscious efforts of recalling, especially with spaced repetition is the best way to learn something. Plus anecdotally decades of experience in learning a huge amount of topics, programming languages, human languages and whatever. If you want to learn something useful I think that it may be helpful for you the course "learning how to learn", already cited by someone else here, in coursera that explains quite well why just skimming and reading a book is a very inefficient way of learning something. Accordingly to that course and a lot of the current learning research I'm not the one that is wrong.