On the flip side, it's taken me a long time to break my skimming habits and read slowly when I'm a novice in a new area. Especially with math or software engineering, it's often necessary to stop at each word I don't understand, unpack it, and gradually build a scaffolding for myself. This is very slow, but it pays dividends extremely quickly.

As a rule of thumb, it seems like skimming is useful if one already have a good familiarity with a subject and the content is slotting into an existing mental framework. However, when that's not the case, skimming gives me the feeling that I've learned something without much real progress.