Sweetspotting breaks down very easily:
Never aim for the player, it's way more difficult
Imagine an box about 3feet square about 1 foot from the bunker
Fill that box with paint on the break and wait for someone to run through it.
In order to be good at sweetspotting you have to:
a) have a good understanding of how to hit someone at distance (angle the guns needs to be at etc)
b) be able to shoot straight
c) fire fast
The way I "get my eye in" for a) is just before game on while everyone is getting sorted, stand at the spot I'll be sweeting from (prolly just in front of the base) and shoot the side of the bunker I will be shooting towards until I am hitting it about half way up (if it's a coke can). I can then judge how hi/low I have to aim to hit that box.
That works for me anyway.....now shooting and running is another matter