[BlueTemplar]

That would be more about philosophical knowledge, not tactical knowledge ?? And on its face, seems to be wrong, care to expand ? (And even some of the greatest fiction might apply here, not only nonfiction, not sure if you were considering that too ?)

[Tycho]

Well what I mean is that eventually one forgets most of what was in a book, and all you remember was whether the book was particularly good. I’m thinking more about literature. So who is better read, the professor who read all of Shakespeare, but thirty years ago, or the student who has only read a couple of plays, but recently, and in depth, and can talk about them fluently and connect the to other works they recently read in depth?

[int_19h]

Speaking for myself, there are several dozen books that I've read several times, and a few with double digit numbers. It's not just a function of that, of course, but also how memorable the book is to you... but it's certainly possible to remember a book so well that even thirty years later you can still do a coherent retelling of it.