Cook was only overseeing nine people when he took over as CEO of Apple (AAPL), which means his management load has increased more than two-fold in almost four years. That’s a pretty significant gain — and one that management experts say may be more than one manager can handle.

According to Hal Gregersen, who heads up the MIT Leadership Center, told Business Insider that the ideal number of direct reports is between six and 12. The optimal number is dependent on how many people a leader can have in a room and still maintain a constructive conversation, said Gregersen.

Gregersen hasn’t studied Cook directly, but said that he has his work cut out for him: “The odds are against any team of 17 versus a team of six.”

For instance, in an hour-long meeting, 17 people would each have three-and-a-half minutes to share their thoughts, versus 10 minutes each for 6 workers. Small groups of people have the ability to go deeper on any one issue.

On the other hand, more direct reports could mean fewer layers of management. Former General Electric (GE) CEO Jack Welch considered that an advantage when he ran the international conglomerate. It allowed “people to flex their muscles,” and it allowed him to “focus only on the big important issues, not on minutiae.”