Porter and HBS dean Nitin Nohria conducted a study of how CEOs manage their time.
They asked a total of 27 CEOs, whose companies had an average annual revenue of $13.1 billion during the study period, to keep track of their time in 15-minute increments for three consecutive months.
One of the defining characteristics of the most effective CEOs, when it comes to time management, is that they're agenda-driven. "A CEO needs to have their own personal agenda that they determine is where they want to spend their personal time" for the next three to six months, Porter said. "They can't just react to all the requests" that come in.
Meanwhile, former GE vice chair Beth Comstock has said that the best leaders dedicate 10% of their daily schedule to "discovery."
In an interview with LinkedIn's editor in chief Daniel Roth, Comstock said, "Can I spend 10% of my time a week reading, going to sites like Singularity, TED, talking to people, going to industry events, asking people: What trends are you seeing? What are you nervous about? What are you excited about?"