Comment by goerz

It's important to realize that lab notebooks (in professonal academic research labs) are quasi-legal documents with specific requirements, in that they must document every modification made to an experimental setup, and every measurement made. It's similar to a ship's log (I presume, not being in the shipping business). This is not about keeping a personal notebook, although there's nothing wrong with applying the rigorous standards of a lab notebook to personal notes. "Lab notebooks" in student lab courses are meant to familiarize students with the practices of genuine lab notebooks, but are obviously much less stringent.