Earlier quoted context omitted.
For me, it helps to slow down my thoughts and aides deep work. I draw diagrams, connect blurbs with arrows, and “link” to other page numbers.
This is still missing the "what" for me. What do you write down about the work? Is it a plan for what you're about to work on? Is it a breakdown? Is it facts you learn as you work through something? Is it a minute by minute journal of what you've done? Is it just interesting details? Is it to-dos? Is it opinions you're trying to clarify? Diagrams I get, my desk is covered in scribbled diagrams to help me visualise so…
A stupid yet accurate analogy is I turn up the log level for my brain lol
It's basically just a log file of everything I did and the result so I can pick it back up later, plus I include timestamps which helps me realize when I'm spinning my wheels for too long.
For building stuff, scribbling diagrams and flows is more useful if I need to work out something complex.