I went to school as an EE and learned in college to keep written, dated lab notes in a notebook without removable pages (to be more credible as evidence).

I did this for years in my earlier career... there's something really nice about using a pen and paper to write down ideas and sketches. I've always felt it was the "linearization" of moving your pen through making a series of marks, one at a time, that helps clarify the thinking process.

Then I actually did get tangled up in a lawsuit, by shareholders against the execs of a startup I worked for, and had all my journals subpoena'ed. It was a harsh reminder that lab notes aren't really your own private sticky notes; if they are ever going to be used as evidence, they are better thought of as a continuous performance of Engineering Best Practices.

I basically stopped writing paper notes then.

I've started journaling my coding again, but electronically (mostly using plain text notes in files, with Johnny Decimal to keep them organized). It's just so helpful during the design and early implementation phase, or when working through a tricky bug hunt. But I usually delete them when I'm done with them.