No One Reads Anything
One of the most surprising things for me to learn as I've grown up is that no one reads anything. There's a set of canonical books that are well respected in various circles. This is Don Quixote for literature nerds, The Mythical Man-Month for software engineers, Atlas Shrugged for the libertarians, and countless other examples for various subcultures. If you hang around any group for long enough, you'll certainly get recommended one of the canonical texts that helps center its beliefs. But if you do actually decide to crack open the book, you'll find that most of its ideas are never discussed.
This is a truth that I first discovered in college. Like many students, I rarely bothered with assigned readings. At best I would skim the recommended chapters and then come to class. It turns out that most professors won't test you on something they didn't directly say in lectures anyways. You really don't need to read if you pay attention in class.
But when I was faced with a particularly difficult semester of courses my senior year, I decided to get ahead over winter break. I bought all of the books for my literature, operating systems, databases, and human-computer interaction classes and dove in, reading some cover to cover before the class started. I got quite lucky here in that my operating systems textbook was the excellent OSTEP which reads quite easily. Other books I read closer to the suggestions in the syllabi, before the classes in which they would be discussed.
What was the result of this pre-reading? The classes were all just review sessions. Almost nothing covered in the classes wasn't just a subset of what I had already learned in the reading. And it was clear I was in an incredibly small set of people who had read any of the text before the class. While explaining concepts, professors would often pause and ask the class how some next challenge might be addressed. If you had read the book, the answer was obvious. I was usually the only one in lecture halls with several dozens of students to answer and not look confused.
OK, I hear you protest, that's college. In the real world, many niche communities are surely well represented by folks who have read their canonical texts. But I haven't found this to be the case.
One thing I continually find is that discussions in these communities rarely relate to many ideas discussed in the text. Even when the topic of discussion is the book itself! There's a few charitable reasons you can imagine for this: (1) There are far more ideas in a book than are worth continual discussion, (2) people agree on the key points in the text and thus don't need to discuss it, or (3) people read the text long ago and aren't remembering what wasn't discussed.
On (1) there's plenty of place to discuss every minute detail of a text if it is worth being discussed. For (2), it seems unlikely given the failure I've seen in these communities to connect the topic of discussion to the canonical texts. Of all of these, only the last feels plausible to me, if folks really are reading what they often claim.
Where does this leave the scholar of these texts? It's a bit annoying to have read these texts and never see some of its ideas bubble up in the zeitgeist surrounding them. But there's also a lot of opportunity there for the careful reader.
My advice is to read as much as you can. Chances are you'll be surprised what you learn. There's so many lessons to learn from reading and understanding. If you feel like you've probably heard everything a book's has to say, you might be surprised what you find when you actually crack it open.