I keep a diary for some projects that I work on. It's basically one large, never ending text file that I keep versioned in git. I like the simplicity of the scheme. It's rare that I need to go back and look at something that I've written earlier. But when I do need to do it, it's there, and easily available. I think I'm going to continue using this scheme for all projects through the rest of my career.
As for logging of structured data, I've sometimes thought of coming up with some kind of annotation scheme, so that, if I need, in my writing, to log a measurable quantity of some kind, I could just annotate it in a special way. And then, later on, if the need should arise, I could just extract the annotated data from the text document. I've not taken it any further, but I think it could be useful. A sort of a "hybrid approach" that would let me focus on the writing and the flow of thoughts, while also letting me log tidbits of structured data in between.
As for logging of structured data, I've sometimes thought of coming up with some kind of annotation scheme, so that, if I need, in my writing, to log a measurable quantity of some kind, I could just annotate it in a special way. And then, later on, if the need should arise, I could just extract the annotated data from the text document. I've not taken it any further, but I think it could be useful. A sort of a "hybrid approach" that would let me focus on the writing and the flow of thoughts, while also letting me log tidbits of structured data in between.