What is it you don't understand lol?
If you're on team 1 you will by default get more sheeping time since your team sets the maximum value. If you last 30 seconds, team 2 gets 30 seconds (at best).
In other words, the performance of team 1 determines how long team 2 gets to play.
Sheep-time is the currency of this game. Team 1 has more of that currency unless both teams get 20 minutes. Hence, it's better to be in Team 1.
In fact, if you're in Team 2 it isn't rational to kill the other team quickly. You should AFK, eat some pizza etc so you're ensured a full round. Killing the other team quickly would just be ruining for yourself.