A true measure of a manager is said to be when he hands over duties to a subordinate. If performance stays on track after the hand off, the manager has done his job correctly. If performance falls, the manager is viewed by everyone as having done a poor job in terms of employee development.
I remember the first seminar I ever attended on management, over 20 years ago now. After the first break, the presenter asked how many had called to check in on the office over the break. When over half of the people raised their hands, expecting a congratulation for caring, the presenter proceeded to tell us that if we felt the need to check in with our people, we had failed. I've never forgotten that reprimand...
The true measure of your success is not whether things run smoothly while you are present, but whether they run smoothly when you are absent. This is true of just about every part of life, not just work.