When I’ve done contract work, and when I ran a startup, I started tracking my own time. I find it helps me focus and account for my time and understand my own habits. It’s not very good for open problems or exploratory work, other than to find that they take a lot of time. ;)

Other than tracking myself, I’ve never had a job that measured my time directly. I had one job that did measure when employees were at work, but they didn’t show it to employees nor set any quotas, they just wanted to understand work patterns.