crunch mode over 75 years ago: It's the single most expensive way there is to get the work done." "More than a century of studies show that long-term useful worker output is maximized near a five-day, 40- hour workweek. Productivity drops immediately upon starting overtime and continues to drop until, at approximately eight 60-hour weeks, the total work done is the same as what would have been done in eight 40- hour weeks."