The conclusion of the Harvard study at the end of the article is revealing:<p>“The gap exists because hours of work in many occupations are worth more when given at particular moments and when the hours are more continuous,” she writes. “That is, in many occupations earnings have a nonlinear relationship with respect to hours. A flexible schedule often comes at a high price, particularly in the corporate, financial, and legal worlds.”<p>A lot of work, especially in management, requires just being available. Your presence, which may not be necessarily required, makes access to your decision-making and input much easier. It's understandable that women who are not completely sold out to the company their entire careers do not make it to the very top rungs in corporate leadership for this reason.