I would say the overhead of time tracking, as a deliberate productivity tool, is barely worth the trouble. For instance, I use Emacs org-mode, where you can schedule and clock tasks in sophisticated ways. It took a long time to setup and get used to the stuff. I thought it might scale in the future. Turns out that pen and paper is much more efficient and effective for me to get anything done on a daily basis. Now I use it more or less to get reminded for some important dates, and to satisfy the sunk cost fallacy. I would only use it as time tracker again, if forced by my employer.