As a systems-minded reader-person:
I like to ask an LLM for 3-5 good ways to know that one really understands the content in question.
Then I ask for examples of each of those, used in a specific setting (code for an app or script I need / project I'm working on, for example).
I also like to pre-read the book based on podcast interviews, YouTube summaries, and so on.
If the book is written from first principles, I will probably find it easier to work through it backwards, as the back of the book is typically where the most functional interfaces to the "world I already know" are demonstrated in such books.
To me this is also a common sign of someone who's a natural systems thinker (since you mentioned the topic): First principles are the wrong end of the learning process.
A natural systems thinker may even hear the phrase "first principles" and immediately start to feel boredom, impatience, and time escaping their grasp. :-)
A systems thinker needs access to working interfaces for systems components first and foremost, not internal components and logic.
This is due to the broad nature of systems work, the interconnectedness of its scope, and so on. Internal logic and single-component foundations focus will effectively block efficiency here.
If it really is more about internal logic of a system's individual component, then this is not systems thinking. Generally here is where you find departure points from systems thinking into more academic-style criticism or analysis. Arguments are definitional in nature and less about work products, economy, or outcomes.
(I also keep a running log and own-structure system if the topic is important to me)
Just some thoughts, good luck.