For all the power CEOs wield, they can’t add hours on the clock or days to the calendar. Yet everyone wants a piece of them: Leadership teams, senior managers, rank-and-file workers, customers, board members, investors, outside groups, the media. And they want their attention face-to-face, on email, by text and by phone, even on weekends and vacations. Add to those demands CEOs’ personal needs — for rest, relaxation, time with family, exercise and doctor appointments. That’s why those running companies have to be very discerning in how they use their hours. Those who do it best are “rock solid clear about what should get their time. They do not have time siphoned away by tasks, meetings and commitments that should really be met by other members of their leadership teams and/or others in the company,” said Dr. Karol Wasylyshyn, an executive coach and author of “Destined to Lead.” On average, CEOs work 62.5 hours a week, according to Michael Porter, director of the Institute for Strategy and Competitiveness at Harvard Business School, and Nitin Nohria, dean of the school. They’ve been conducting a long-term study on how CEOs spend their time. They ask CEOs to keep track of how they spend every hour of every day for three months. So far, they have 60,000 hours of data from 27 CEOs of large, mostly public companies. The study also found that CEOs spend about 4 hours a day working on most weekends; and about 2.5 hours a day during most vacations. But how they use their hours determines how successful they’ll be. “The way CEOs allocate their time and their presence … is crucial, not only to their own effectiveness but also to the performance of their companies,” Porter and Nohria wrote in the Harvard Business Review. Here are some of their recommendations: With meetings, shorter is sweeter CEOs reported that about a third of their meetings lasted an hour on average, while 38% went longer. “‘Standard’ meeting times should be revisited with an eye toward shortening them. Doing this can significantly enhance a CEO’s efficiency. In our debriefs, CEOs confessed that one-hour meetings could often be cut to 30, or even 15 minutes,” Porter and Nohria reported. Make time to be alone CEOs are supposed to set a vision for their companies, lay out broad strategies to realize it, and clearly communicate both to stakeholders. That’s hard to do without adequate time to reflect. On average CEOs spent 28% of their work time alone, but the majority of it was in blocks of an hour or less. “CEOs need to cordon off meaningful amounts of alone time and avoid dissipating it by dealing with immediate matters, especially their in-boxes,” Porter and Nohria recommended. Delegate more Getting too involved in the day-to-day can derail CEOs from putting their time where it’s needed most. For example, with reviews, CEOs can become too mired in company operations, Porter and Nohria noted. “We have found, again and again, that many have a hard time shedding the COO or president roles they may have previously held. Some also forget that their senior team should bear the primary responsibility for many reviews and keep the CEO informed on a regular basis.” Use email less CEOs reported spending 61% of their work time in face-to-face interactions, and 24% on electronic communications. While email can be an efficient way to communicate, it can also be a time suck. “CEOs should recognize that the majority of emails cover issues that needn’t involve them and often draw them into the operational weeds,” Porter and Nohria said. Having an executive assistant filter and delegate them before you even see them can help. What’s more, sending too many emails can be counterproductive, they added. “Emails from the CEO can create a downward spiral of unnecessary communication and set the wrong norms, especially if the CEO sends them late at night, on weekends, or on holidays.” Don’t schedule every minute CEOs in the study spent about a quarter of their time on average on spontaneous interactions. That’s critical, the authors assert, so executives can be available for opportune conversations or meetings and to deal with unfolding, unexpected events, which consumed about 36% of CEOs’ time. “Leaders whose schedules are always booked up or whose [executive assistants] … say no to too many people risk being viewed as imperious, self-important, or out of touch,” Porter and Nohria noted. Keep in touch with employees CEOs spent about 14% of their time with low-level managers and 6% with rank-and-file workers. That’s time well spent. “[CEOs] must stay approachable and find ways to meaningfully engage with employees at all levels. This not only keeps them in touch with what is really going on in the company but helps them model and communicate organizational values throughout the workforce,” Porter and Nohria advised. It also helps CEOs better understand their employees’ experiences, which pays dividends down the road, they noted. “Relationships with employees at multiple levels also build a CEO’s legitimacy and trustworthiness in the eyes of employees, which is essential to motivating them and winning their support.” Make time for your life CEOs in the study seemed to get the memo that they needed to rest and stay healthy. They slept nearly seven hours a night on average. About 9% (or 45 minutes) of their non-work time was devoted to exercise. And of the 25% of their time (or six hours a day) spent awake but not working, half was time spent with family. “To sustain the intensity of the job, CEOs need to train — just as elite athletes do. That means allocating time for health, fitness, and rest,” Porter and Nohria recommended.