[qumpis]

I think it's a great advice. I'd also add that reading a book from cover to cover without a clear application of the knowledge can be wasteful in terms of time and retention, and might lead to feeling motivated to finish the book as opposed to understanding it.

Learning on the fly for me personally is a more suitable approach: determine what I'm lacking and build a dependency graph of things I need to understand before achieving it. The n conquer the individual topics.