> A much better example of the benefits of slack would be a CEO who delegates the day to day work ... to give himself slack -- more time to think about big picture things and consider ways to change the organization to make it better.

That's not slack. As you just pointed out, that's his regular job. Slack is unscheduled time, not time that's devoted to performing your duties. The point of slack, anywhere, is that it lets you respond to situations that arise, by converting the unscheduled time into time in which you respond. If you're fully scheduled, that's difficult to do.