Since I started note-taking a few years ago, my productivity has increased dramatically. The biggest benefit is that you can stop working on an idea for a bit, then come back later and read it back from disk to main memory, often now seeing issues with what you have written down that are apparent now, but were not back then.

Writing a paper about your idea is the ultimate form of this, but of course most of the time overkill. But it is good to bundle everything up in a paper once enough stuff has accumulated.