A research journal should be dated.

Evergreen notes are mutable, which makes it hard to acknowledge and mvoe through the changing nature of my motivations and interests. It makes sense to date my changes, and where possiblr to preserve at least summaries of older perspectives, to see how I've moved forward in a thought process. APIs are rigid, which means I can change my mind about the shape of my notes so long as I don't depend on the shape too much; but it also means, that as long as I stay married to old strucutre and content, I prevent myself from moving forward.