One movie condition you may want to consider is:
Luke Skywalker deflecting blaster shots with his pee saber.
It seems that no matter how many people are shooting at him, he deflects them all, even when shot from behind.
He can sense shooters behind him with the force.
This would be the extreme condition that you might want to allow and design for.
You also have to remember the "Stormtrooper Effect", which causes a massive amount of grunt troops who are all firing at the same target to miss every one of their shots or have them deflected back at them...