If you raise the attack or sp attack via super training they do more damage as an upgrade. Rapid fire is good for dodging though as you don't have to wait and shoot.
Once you get the routine you'll notice that you usually take out waves of white squares usually 2 leading to a red weak point square, thats when you charge up your shot and let rip. Only other thing is you can hold it down and release when needed to set up a continuous barrage. Actually if you use the charge shot at that time you are vulnerable as you stop before firing.







