I wrote How to quickly become effective when joining a new company ages ago. It's about how to learn in an environment where:
The strategy described is I think useful outside of that scope, but I suspect there are better strategies when those are not your precise constraints.
I've been using a Read/Code/Bike/Repeat learning strategy a lot recently.
How does this work?
And basically repeating this process until I feel satisfied with my understanding of things.
Obviously this doesn't require an actual bike ride. Anything which disconnects you from external influences will do, but I think the exercise element might actually be a helpful part of it.
The problem is that in general it’s really hard to write books for the “expert” because every expert is different. If you’re writing a book for use as a reference manual that’s fine because you can just make it a bunch of self-contained sections, but if you want to write something intended to be read from cover to cover I think the best you can really do is write something targeted at beginners in increasingly specific niches.