I'm biased - I work with lab scientists fairly heavily, so "You don't keep a lab notebook!?" would be met with shock and horror, even though they recognize that most of my work will never go near a lab bench.
But yes, it helps me in my job. While I heavily comment code, there are decisions that are made in the code, and the development of projects, that might take paragraphs of explanation. Or pictures. Or back and forth with myself. A notebook both allows those internal thought processes to be documented in a meaningful place - complete with random side ideas like "Could multiple imputation fix this?" - and allows me to refer back to them to job my memory as to why I chose one concept over another.
It's let me do things like pick up a project and not only know what/why the code is doing (comments), but why those things got coded, while other questions didn't. In my case, it happens to actually be a physical journal.