William the Conqueror, though voracious in war, recognized the need to promote stability in times of peace. Henry I and especially Henry II spent themselves in developing a solid governmental structure. I think, in most cases, the leader himself must be a good manager. This is different from much contemporary advice.
I think sometimes we as leaders deceive ourselves into thinking that we can set the course and let able administrators manage. I think the best leaders can do both. And in the absence of an able administrator we had better do both.