Perfect Productivity: 52 Minutes work, 17min Break?

"the brain is a muscle that, like every muscle, tires from repeated stress. ... more hours doesn't mean better work. Rather, like a runner starting to flag after a few miles, our ability to perform tasks has diminishing returns over time. We need breaks strategically served between our work sessions. So what's the perfect length for a break? Seventeen minutes, according to an experiment released this week." - A Formula for Perfect Productivity: Work for 52 Minutes, Break for 17 - The Atlantic