But the conventional wisdom in many workplaces today is "everybody knows that working crazy hours is what it takes to prove that you’re “passionate” and “productive” and “a team player” — the kind of person who might just have a chance to survive the next round of layoffs."
Why crunch mode doesn't work, a study prepared for the International Game Developers Association, combats this conventional wisdom with a historical survey of the research which found that longer than 40 hour work-weeks simply do not pay off.
From The Prosperity Covenant:
That output does not rise or fall in direct proportion to the number of hours worked is a lesson that seemingly has to be relearned each generation. In 1848, the English parliament passed the ten-hours law and total output per-worker, per-day increased. In the 1890s employers experimented widely with the eight hour day and repeatedly found that total output per-worker increased. In the first decades of the 20th century, Frederick W. Taylor, the originator of "scientific management" prescribed reduced work times and attained remarkable increases in per-worker output. [emphasis mine]
Past the eighth hour of work in a day there exists no 1 to 1 correlation between hours worked and productivity. That is to say, increasing the hours 50% does not obtain 50% more production. This goes for office work as well as factory work and even for managers. "Follow-up investigations on the Exxon Valdez disaster and the Challenger explosion ... found that severely overworked, overtired decision-makers played significant roles in bringing about these disasters. There’s also a huge body of research on life-threatening errors made by exhausted medical residents, as well as research by the US military on the catastrophic effects of fatigue on the target discrimination abilities of artillery operators."
… research shows that knowledge workers actually have fewer good hours in a day than manual laborers do — on average, about six hours, as opposed to eight. It sounds strange, but if you’re a knowledge worker, the truth of this may become clear if you think about your own typical work day. Odds are good that you probably turn out five or six good, productive hours of hard mental work; and then spend the other two or three hours on the job in meetings, answering e-mail, making phone calls, and so on. You can stay longer if your boss asks; but after six hours, all he's really got left is a butt in a chair. Your brain has already clocked out and gone home.
Sorry, but managers will most times have to hire more people if they want more work done.