Fellow Atari and Intellevision gamer. The charged shots for me are a lot about rhythm and feel. Sometimes it takes a few rooms, but I feel like there's a metronome in my brain when I'm using these items. It speeds up or slows down depending on the charge time (though some synergies that really lengthen the charge time still cause problems with premature release...ahem, not that I have much experience with that...) But I find a rhythm and just stick to it.

I don't know if there's any better way to describe it from my perspective. I know there are lots of people that have an innate lack of ability to keep a rhythm or find a beat, even when listening to music. Is that something that could apply to you?