I own nice notebooks. I like the small Moleskine book with dots rather than a grid or ruled lines. I also like the Rhodia books because they're a little easier to use and maybe less formal (can a notebook be formal?). I like to make sure I use the same pen all the way through. Sometimes I start at one end for work notes and the other end for personal stuff, and they eventually meet in the middle.
I like all of that. But the vast majority of my notes are text messages to myself or frantic scribbling on the back on an envelope or some instructions for a recent IKEA purchase. Why exactly did I write 'fish', with no other context?