Managing others means you have a lot of extra duties. If you're not effectively delegating tasks to those best suited to doing them, however, you're not doing the job you're paid to do.
As business blog Inc points out, all too often managers and bosses can get hung up on whether or not things are getting done exactly the way they want that they forget what their job is. A manager's job isn't to do everything correctly. It's to hire and direct the people who can do it well:
"You can't grow or scale your business quickly if you're making all the decisions. It's not about you," warned Vinod Khosla. The billionaire has had a few notable failures, but is best known as a co-founder of SUN and a pioneer in venture capital at Kleiner Perkins and his own firm, Khosla Ventures. "It's too risky to bet year after year on a company that depends entirely on one ego." The job of a leader is to "recruit and develop people who can make better decisions than you. What you're looking for in leaders is the ability to build the teams that can make decisions on their own -- while the leader asks great questions and provides guidance. They're more of a beacon than a commander," he smiled.
Of course, you don't need a fancy job title to apply this to your own life. Anyone who is in a position to direct others has to learn that working with the right people is just as important as making sure the work is done right. And if you pick the right people at the start and instruct them well, you should need to check on them less.