How to forget what you read

But reading is the first step. You never learn only by reading. You have to relate the ideas with your prior knowledge and practice it or apply it somewhere.

You also have to get a nice book. And have to practice reading. Reading is a skill, it's an extension of imagination. You have to practice that, and reading is an awesome way.

I read with a highlighter pen, just highlighting the places I find interesting, and maybe cornering a few pages once in a while. That costs no more energy than just reading the book, if anything highlighting allows my mind to stay focused on the book.

couple weeks after the book is finished, I'll come back only to the highlighted parts and write some of them down in a a4 page, which I then fold in the book.

That way I have a personal 1 page book summary which I come back to from time to time.

I liked an idea I saw on Youtube from someone saying "for each chapter, I find something actionable I commit to do for a week". A bit on the heavy side, but I like the actionable aspect of it

Exactly. Spaced repetition is a remarkably effective learning technique, but it can't tell you what to learn.

At some point I think we have to stop listening to external authorities and rely on our own judgement about what to learn, and how to do so, as signalled by feelings of excitement about particular authors and ideas. One of the effects of formal education is to dampen or corrupt that intuition, e.g. by instilling the desire to learn things 'properly' (say in a certain prearranged sequence) or by the desire to only learn prestigious topics in order to impress other people.

If we are engaged meaningfully with reality we will inevitably revisit particular subjects or authors multiple times. This is an organic form of spaced repetition. Forgetting certain things is part of that: we learn to swim during the winter and to skate during the summer.

I've found non-language topics to be more challenging. Whether or not a card is useful depends largely on how well written it is. You need to find the right wording which captures the essence of the point while remaining simplistic and atomic enough that the card doesn't become tedious to re-visit. I'd argue that the process of crafting the right card is equivalent to digesting it and synthesizing your own thoughts on it. I'd also argue that if you believe Anki positions itself as a "shortcut" then you've probably used it incorrectly. It is indeed true that you get out what you put in, and low-effort Anki cards will most likely end up being abandoned or deleted. Useful cards require effort, the same as any other learning/memorising technique.