Well if you write down a snippet of code, and later upi reliaze you need that code a gain but don't remember it but do remember that you must have written a note about it, then writing down the note was useful.
The issue I'm still working on is how do I find such notes when I don't exactly remeber what they were about.
> how do I find such notes when I don't exactly remeber what they were about
I can't claim to have solved that; but I do have a personal rule about notes. I don't create a note unless (1) I'm willing to endow it with at least some metadata, and (2) I'm willing to manually link it to another note so that I've at least dropped one breadcrumb.