The perfect number of hours to work every day? Five

Note that the 5 hour work day proposed in this article isn't about working less. It's about compressing the same amount of work into a smaller window of time.

The claim is that the compressed working hours increases focus, urgency, and efficiency. Employees were asked to do their work in a 5 hour block with no breaks at all.

From my own time tracking, 5 hours of work is about right for an 8 hour work day if I'm also taking breaks, grabbing lunch with coworkers, having short catch-up conversations with people (outside of scheduled meetings), and stretching my legs for a while every hour.

I could probably do the 5 hours of work in a single 5 hour block without leaving my desk or taking any breaks if I really tried, but I'm not sure I'd want to. I might get an extra 3 hours back in my day, but is it worth it if I'm exhausted and feel like I can't allow any time for socializing with coworkers?