If you value money, you’ll budget and track track it. Why not treat your time the same?
When I worked at a large engineering consulting firm, every minute of my working day had to be attributed to a current project. I worked on various large projects for different clients throughout the day, but by 5 PM my time had to add to 8.0 hours. If a project had too many hours it would go over budget.
Since there was no category for ‘walking around’, ‘chatting it up’, or even ‘misc work’, it encouraged a productive, task-oriented mindset.