[mtippett]

My background theory is around schematization. Our knowledge is a complex web of inter-related concepts. Some factual, some abstract.

For audiobooks/read books, I look for 2 or 3 key "aha moments" that stick with me. For Thinking Fast it was "two ways of thinking", "loss aversion". From there other related concepts are just below the surface.

For Thinking in Systems it's "stocks + outflows + inflow", and "all systems reach an equilibrium".

As you read more, you get lots of different ideas cross pollinate, and from there you gain your own insights.

As others have said, pondering or applying the ideas in real life is really important.