Delegation is a critical part of leadership. There is a limit to how productive one person can be. You can't stretch time. As a leader, the limit to how much you can improve your productivity is flexible. It all depends how you structure your team. If done properly, you and your team can collectively deliver hundreds of hours of work per day. Your job as a leader is not to do all the work yourself, but rather help your team. You need the right team, and you need to delegate to the team.
Delegation has two parts: what you should delegate and how you should delegate.