Evan’s 6 Lessons.
Lesson One, then, is this: Productivity varies over the course of the workday, with the greatest productivity occurring in the first four to six hours. After enough hours, productivity approaches zero; eventually it becomes negative.
Lesson Two, then is this: Productivity is hard to quantify for knowledge workers.
Lesson Three is this: five-day weeks of eight-hour days maximize long-term output in every industry that has been studied over the past century. What makes us think that our industry is somehow exempt from this rule?
Lesson Four is this: At 60 hours per week, the loss of productivity caused by working longer hours overwhelms the extra hours worked within a couple of months.
Lesson Five is this: Continuous work reduces cognitive function 25% for every 24 hours. Multiple consecutive overnighters have a severe cumulative effect.
Lesson Six is this: Error rates climb with hours worked and especially with loss of sleep . Eventually the odds catch up with you, and catastrophe occurs. When schedules are tight and budgets are big, is this a risk you can really afford to take?
It comes down to productivity. Workers can maintain productivity more or less indefinitely at 40 hours per five-day workweek. When working longer hours, productivity begins to decline. Somewhere between four days and two months, the gains from additional hours of work are negated by the decline in hourly productivity.
I still run into managers who believe that long hours will help bring the project in and by enforcing long hours they are teaching people how to “work hard.”
This belief persists because it is hard to quantify productivity for knowledge workers. But it’s not terribly hard to count defects or see the relationship between work actually completed and work remaining when you count in the new work from defects. When you measure only hours, the dynamic may remain hidden. But you’d think that when the project still didn’t finish at the desired time despite long hours, people would begin to question their assumptions.
Maybe the studies Evan cites will convince some people.
Read the full article here.