Some of them do very simple things—jotting a few key references on the back page, or writing intermittently in the margin—but none of them implements any kind of consistent practice like the one described in Write about what you read to internalize texts deeply. It’s not that they’ve so deeply internalized and automatized those practices that they seem invisible: they’re just not doing those things.
They’re all expert readers, though, in their own way. They read for a purpose; they discuss what they read with others; they use what they read as part of creative projects; etc. So they’re not more effective than other readers for no reason at all.
In fact, the negation almost seems true: most note-taking fanatics seem to actually be quite ineffective thinkers. This should give one pause that it’s important to Write about what you read to internalize texts deeply! I suspect that the key issue here is “Better note-taking” misses the point; what matters is “better thinking”; such people are focused on “better note-taking.” People who write extensively about note-writing rarely have a serious context of use.
That said: Many eminent thinkers need a writing surface to think.
Here’s a more optimistic take. There are (and have always been) people who don’t write notes and are very effective. On the margin, writing may not help them much. But effective people are rare; most people aren’t. On the margin, writing may allow otherwise-ineffective people to join them. And we wouldn’t necessarily see this effect in the distribution of people out in the world, if e.g. writing were culturally unpopular, or if getting the benefits required special techniques/knowledge which were not widely known. I think it’s likely that this conjecture is true to some extent, but I’m not at all confident that the effect size matters.
Many bloggers and “life-hackers” have made a full-time job of suggesting how you should organize your journal, or how you should most effectively Write about what you read to internalize texts deeply. We should take this advice seriously insofar as those practices have helped the authors achieve meaningful creative work: “Better note-taking” misses the point; what matters is “better thinking”
But most people who write about note-taking don’t seem particularly accomplished in their own fields, whatever those may be. In fact, most such writers aren’t applying their notes to some exogenous creative problem: their primary creative work is writing about productivity. These writers offer advice on note-taking to help scientists and executives with the challenges of their work, but the advice was developed in a context disconnected from those external realities. There are two related problems here: Effective system design requires insights drawn from serious contexts of use, and Powerful enabling environments usually arise as a byproduct of projects pursuing their own intrinsically meaningful purposes.
Luhmann, by contrast, barely wrote about his Zettelkasten: he focused on his prolific research output, then published a couple small essays about his practices near the end of his career.
I’m not quite guilty of this problem myself, but I certainly slip into this behavior for weeks at a time. This is a cautionary note. Related: The most effective readers and thinkers I know don’t take notes when reading.