From my perspective, in most cases and for most people, saying they work X hours is kind of meaningless. However, for the top 1% of people with the intellectual firepower like Marissa Mayer, the Google founders, Elon Musk, etc., their number of hours probably directly drives massive value creation, problem solving and great accomplishments. Thus if that’s what Marissa said, I would tend to agree with it. Great things sometimes just take time x intellect.