A slacker's guide to productivity - The Week
Eric Barker stashed this in Diabolical Plans For World Domination
You had me with the very first point of the six.
1. Work less
Working too hard for too long makes you less productive.
Yes, pulling 60-hour weeks is impressive. But pull them for more than two months and you accomplish less than if you had only been working 40-hour weeks.
One study, on construction projects, found that "where a work schedule of 60 or more hours per week is continued longer than about two months, the cumulative effect of decreased productivity will cause a delay in the completion date beyond that which could have been realized with the same crew size on a 40-hour week." [Scarcity: Why Having Too Little Means So Much]
(The best system for time management is here.)