In the book Building a Second Brain, Tiago Forte makes this statement:
…in any piece of content, the value is not evenly distributed. (Emphasis his)
Which is a true statement. It’s also a statement many fake gurus use as part of a “read more faster” tip. “Just read the table of contents then skim for the headings” they say. “You’ll get 80% of the message in 20% of the time.”
Well, that’s a shitty use of both Forte’s point and Richard Koch’s 80/20 Thinking. As much as the value of content isn’t evenly distributed, value isn’t even distributed per reader or per reading. It shifts based on the individual at that moment and the individual at a future moment in time. With great content, not only will those original points still be relevant years later, but the content in the valleys between those peaks will emerge in value and meaning. Whereas with shitty (*cough* Kindle Unlimited 80 page self-help garbage *cough*) content, the value of even those bold heading will fade.
It’s what I both encourage highlighting/note taking/marking the page at the top (to borrow Cal Newport’s method) while reading through a book, then reading through it again. Not just the parts you highlighted, which I’m assuming you put into a second brain or slipcase or commonplace book. If you just read over the highlights, you’re missing the content that reveals that value, and that in time will have value all on its own.