Reading without note-taking is the time wasted. Proven more than once.
The main reason is that we confuse the feeling of understanding with the feeling of learning. If the first is that we are just "understand what is said in the book", the second is that we "understand it, memorized it and ready to put it into practice." As we just read, the brain signals us about reading comprehension, but real understanding is possible only in the retelling what we read in our own words or, better yet, applying it in practice.
In my experience, there were several cases when I have reread the same book 2-3 times in a row, without note-taking, after which it successfully vaporized from the head in a couple of weeks. When I tried to read it few month later, I read it like in the first time. At the same time, only one-time summarizing it enabled me to finally, truly understand its meaning and begin to apply it in practice.
Once again, this is extremely important: the consumption of educational literature in the passive mode, without note taking only creates the illusion of understanding and learning, in fact, we neither fully understand, nor remember most of what we read.
Infotainment - entertainment under the guise of self-education, one of the most popular ways to procrastinate :)
An extremely important thing about summarizing what you read: it has to pass through your head, not become the copy/pasting of sentences and chapters. You should try to express all thoughts and ideas in your own words, it's the only way to understand and remember them. And the farther your text, words and expressions are from the original, the more you learn.
It's not necessary to rewrite the text in your own words, you just need to write down the thoughts that arise in your mind. The don't even have to correspond to the text of the book - the thoughts and ideas are valuable by themselves. The fact that they originated in the process of reading this particular book, is making them an integral part of the notes.
Writing summaries is the hard work. And like any other hard work, it should be treated responsibly, otherwise, the benefits will be minimal. If you feel that you lose concentration - you should immediately put the book aside. There is no profit from thoughtless rewriting, in this case there are plenty of much more pleasant and useful ways to break away than aimlessly strain your eyes and brain.
An ideal summary format from my experience comes in short thoughts, each of which is decorated in the form of points. Thus it is necessary to accustom yourself to short, throwing everything superfluous without loss of meaning. If the thought or idea does not fit into a single short sentence, it can be either cut or divided into several ideas.
The purpose of note-taking is to get a set of ideas that you can put into practice either immediately or in the near future. Instead of an "abstract", you should get a "list of actionable ideas."
Learning anything implies the immediate applying what you learned in practice, so taking notes must be treated solely as a preparatory work, which time is not in the mornings, but in the afternoons. It's much more effective to dedicate mornings to the practical application of the knowledge gained.
Thus it is necessary to catch the sudden motivation spikes and immediately get back to work. There is nothing more valuable than motivation. When you don't finish a book, you will get a feeling of incompleteness, but it's only a psychological phenomenon, there is no harm from it.
As a result, there will be a bunch of incomplete summaries, but much work on the ideas you learned. It's more effective to immediately put into practice even a small and simple idea, rather than finish summarizing the whole book to the end, wasting such valuable motivation. There should be no regrets if you start new summaries on the "corpses" of the incomplete ones, the main thing that is important is how these new ideas add value to your current projects.
I repeat once again: the value of note-taking - not to "check" that we "mastered" a certain course or book. Its main value is in the flow of ideas and motivation to act on them right now. That is, the selection of books should be in the way that supports the ongoing work, not to put it aside.
Do not make yourself a long line of books waiting to be read. Instead of this "line", there should be an unordered list of topics that could be learned in the future. When you feel "plugging" in the ongoing work, it will be easy to choose the most appropriate book, and start or continue its summary exactly to the moment you get a cool idea.
Got an idea and motivation? Get back to the work, do not waste your time and motivation!
When I suddenly lose the motivation I re-read my old summaries, or start a new one. From my experience, re-reading the old is more effective than summarizing new, because it gives a more dense stream of ideas and does not require much time and effort.