Nate Solon has just provoked with a blog on Lichess:
Why Chess Books Don't Work
He has some point -- I mean, if books made you a better chess player, I should be world champion by now...
But I commented, crossly:
To the extent that Chessable has a theory of learning, it's a very impoverished one.
I believe Pillsbury was once challenged to remember a list of obscure words, starting Antiphlogistine, Madjesoomalops etc
Spaced repetition/recall seems perfect for this task where any meaning in the content is irrelevant.A book will have, as you suggest, an implicit theory of learning, but I suspect will be richer than you give it credit for, perhaps having several on one page. I don't know if you know the book Winning Chess by Chernev and Reinfeld -- I suspect both authors would struggle to articulate a 'theory of learning' of the sort you seem to think is required, but what a great pair of teachers.
I know many books from Everyman which use the Socratic method, of presenting a question before giving an explanation.
Others engage with wit, colourful language, striking examples, slogans, scaffolded exercises etc. Implicit maybe but Ford save us all from learning opening lines by rote.Good-quality verbal explanations in books can unlock a whole opening system for you, as can a good example.
The right book at the right time can produce a step-wise improvement -- I can remember two or three from my early playing days (Winning Chess Chernev/Reinfeld, Middle Game I & II Euwe/Kramer, Secrets of Practical Chess Nunn).
Perhaps the reason most books don't 'work' is because most books are not good books -- or not good for you at the time.
I can remember acquiring, on Silman's recommendation, the book on Combinations by Znosko-Borovsky. I learned nothing from it, as Chernev/Reinfeld had done their job well. I also learned next to nothing from Fine's Basic Chess Endings -- it was far too advanced for me when I picked it up.