Work Less, Get More Done: Analytics For Maximizing Productivity:
There is no possible way for me to achieve results like that merely by lengthening the number of hours I work in a day. Additionally, because I’m capable of producing like that (via, e.g., leveraging freelancers intelligently in a business process which uses software to make them efficient and then extracts business value out of their labor), there is no need to spend excessively long hours working for the sake of working.
The basic premise is: ROI your time. Not how much time you spend, not how effective you spent it, but how much you get in return.