Teachers

Think of the best teacher you ever had in school. Could she successfully teach a class of 200? Or 500? Of course. She might have to figure out how to test/grade that many students, but she could definitely hold their attention and communicate clearly.

Now think of the worst teacher you ever had. Could he successfully teach a class of only 4 students? No. He was incompetent -- didn't matter how few students he had. Schools freak out about student:teacher ratios, but this ratio is not necessarily correlated to how much students actually learn.

Same goes for any kind of leader. A good leader can command an army; a bad leader can't control a boy scout patrol. Organizations (schools, churches, companies, etc.) should divide the people who need to be led by the number of leaders, not divide them into groups and then try to scrounge up people to lead them just for the sake of having convenient groups.