I know I have been able to do this before (like a year or two ago), but what is the trick to complete this goal? I have used an hour spraying all over the place even remotely close to the arrows. I've got exactly twice one spot sprayed, never even two, even if I'm playing with the easiest level (3 minute limit). What's the key to this goal?
Either this has to be clearly the hardest cap/goal in the whole game, or then I just really don't understand the way to do this. Please help me.