On a slightly different note, I'd like to say that knowledge should be applied from general to specific.
In a chess game, you only to need to keep in mind, at all times, the general strategy (piece activity and material). When a more specific, applicable rule comes up, you will automatically know it and how to deal with it, but you shouldn't keep all these rules in your head.
This is how to play decent chess without knowing that much about chess.
There have been several threads lately about books, topics (tactics, openings), etc. here asking basically the same question: how do you learn (improve) in chess?
Since most of us here don't have professional coaches, I thought I'd share my insights in Cognition and Learning as a teacher with an Advanced Professional Certificate.
There are five levels, called the "Dimensions of Learning" that distinguish the different kinds of things we learn from rote memory to abstract thinking and including whether we apply basic skills or adapt skills to new things. I'm not going to confuse this message by getting into them, I'm going to say that we low to intermediate level players do not recognize basic patterns and tactics as well as we should, so our learning should be more rote than abstract (more tactics than strategies) - though obviously applying tactics learned in one position to a similar position requires abstract thinking.
Concentrating on basic learning, then, note there are five ways we accumulate knowledge with our senses and we learn BETTER the more of them we use:
1) Kinesthetic: hands on: writing down information with a pen/pencil, physically moving the pieces or moving a mouse to move the pieces, etc. in an actual game or drill.
2) Seeing: videos about chess
3) Reading: Studying text words in books
4) Visualization: Diagrams, special symbols indicating relationships, visualizing the actual chess pieces instead of seeing the letters "King" etc.
5) Speaking/Hearing: giving yourself a speech or going over a set of instructions out loud, listening to an video or audio lecture.
Some of us learn better reading about something, others seeing/hearing an instruction video, others actually building or moving something around, etc. But ALL of us learn better if we get the same information in as many of those 5 ways as possible.
Consequently, working tactics problems should be a good method of learning since you move pieces on a board or screen and are learning in both kinestetic and visual ways.
So what to do if you read a book? You will learn faster if you write/type an outline or a summary of each chapter or each major topic - then, out loud, give yourself a 1 minute speech about it.
The same with videos. There's one here at chess.com called "The Five Forks You Should Know." Can you name the five forks off the top of your head? Can you describe each one? I can NOT - I'm watching that video soon! These are the basic building blocks of chess and we want to improve but we don't know them. I just watched the beginning (it's a 26 min. video) and they are:
1) Knight Forks
2) Pawn Forks
3) Double Attacks
4) Tempo Forks
5) Loose Squares and Pieces Forks.
Now, I just listened to IM Daniel Rensch state them, then I read them as the words were printed on the screen, then I wrote them here. They are now in my short-term memory and, at age 66 I needed all three steps to retain their names alone! Next is to learn to describe each one: to watch/hear the whole video and write/type notes, then give myself a 1-2 minute speech about what I learned.
That is how skilled teachers design a learning program - working the brain in as many different ways as practical. So once you decide what you're going to study, whether it's tactics or openings or endgames, etc. You need to look at what's available to you and put together a multi-sense way of retaining learning!
Good luck!