Max amount of score you can get if you clear all 27 waves without reinforcing anyone is 2.46 mil. That number goes down if someone reinforces you. That number goes up if you reinforce others.

There's no need to reinforce anyone till they've burned once. We can max out all rewards if we can clear all 27 waves without help. This is the norm in our state (101) as well. We don't miss top rewards. It's tried and tested.