I agree with gist of the article, but the following passage is unclear and could use elaboration: "Phone calls: I schedule almost all phone calls, except for o

I agree with gist of the article, but the following passage is unclear and could use elaboration: "Phone calls: I schedule almost all phone calls, except for ones with high priority people. This high priority ones interrupt whatever I’m doing or get done on a drive to and from the office." Does this mean that if he does a phone call, he's usually the one who schedules it? And how does he determine who is a high/low priority person? Is his assistant a control point in this regard? Does he generally refuse inbound phone call invitations? Do people in his company know not to send him phone meeting requests?