Reminds me how the original Mac Finder took spatial memory very seriously. Wherever you moved something on the desktop or within a particular folder, it stayed there.

That’s definitely a design principle that’s been long since lost.

I agree with the spatial memory and the many possible and valid ways to approach reading and learning. But it's much harder to recall, connect and leverage ideas that way

I used to take notes on loose sheets of paper, fold them, and stuff them into the book between pages. I guess there are lots of ways to build a system.

A few books I've taken enough notes to collect them in a folder. I put section tabs in the book and tabbed dividers into the folder with matching colors. I note the page numbers for each note. Then I shelve that folder to the right of the book it was noting.