In many shows in the last few decades there have been teams of five people. Some people wonder, why five? There could be many reasons why. They could provide episodes for background story or you could cover the personality spectrum to appeal to everybody.
Why would you want to appeal to an audience because of personality? Well would you want a character you could relate to or none at all? Even if it is one thing in one character it makes the show much better if you can feel the emotions of the character or understand the decision they make because you would be following their thought pattern.
What if you run out of episode ideas to continue the plot for your show? Well, you have five characters to choose a backstory from! Those episodes could give new ways to new episodes and new characters! These background stories could make or break a character. They could become hated by the community or more loved.