A person who works six hours a day but with total focus has an enormous advantage over a 12-hour-per-day workaholic who's "multi-tasking" all day, answering every phone call, constantly checking Facebook and Twitter, and indulging every interruption. It's time we upgraded our work ethic for the age we're living in, not our grandparents' age. Hard work is still a virtue, but now takes a distant second place to the new determinant of success or failure in the age of Internet distractions: Control of attention. Hard work is dead. Are you paying attention?
From Lifehacker There must be some good research on this - will go look.