Peter Macdiarmid/Getty ImagesWhile researching her books on time-management and productivity, Laura Vanderkam would ask people, "How many hours do you work every week?" Often she'd get an answer like, "Sixty, because I'm generally in the office from 8 to 8." Then she'd ask, "How many hours did you work yesterday?" Inevitably, she'd hear something like, "Oh, well, yesterday I was a little late.