A tip for writers from Douglas Wilson, Wordsmithy: Hot Tips for the Writing Life (Canon Press, 2011), pages 36–37:

We test students right after they read something mostly to ensure that they have in fact read it. From this, many have drawn the erroneous conclusion that the only good that can be extracted from the reading is that which can be displayed on or measured by such a test.

This is wildly inaccurate. Most of the good your reading and education has done for you is not something you can recall at all. . . .

Mark every striking thing that you read. You won’t remember everything you read, and you won’t even remember everything you mark. Nevertheless, it is not a sin to remember some things or to mark them in such a way as to be able to find them again. I use blue highlighters on everything, to such an extent that one of my granddaughters assumed, reasonably enough, that this is what I use whenever I am “coloring.”

But you are not cramming for a test. You are simply marking things because this is a good way to read with your eyes open. You read widely to be shaped, not so that you might be prepared to regurgitate. Read like someone who can afford to forget most of what you read. It does not matter because you are still going to be shaped by it.