I have to spend a significant amount of time with this group of people because they are the ones who have to know my heart and the reasons why I make the decisions I make. If my relationship with one of these people is even the slightest bit off, it could end in huge disaster.
Your setting might be different, either larger or smaller, but you must have a core team of leaders that you surround yourself with. No one can do ministry alone and no one can lead effectively by themselves. I work best in teams and this team is the one that I pour my time and energy into!