if you stay down on the shot long enough to see it hit the object ball (if you dont you should..jmho )
1) do you miss because you dont hit what you were aiming at most of the time???
thats flaws in your fundamentals not aiming
2) do you miss because you hit where you were aiming and it was the wrong target??
i would bet $1.50 that the majority of you miss because of #1 not #2
so work on your stroke will get you farther than an aiming system
But some have serious aim issues, for example, not aiming to the true pocket center for most shots. Then they swerve during the stroke, often subconciously.
It's what you wrote (straight stroking) but also, commitment during play.
Weak players tend to focus on immediate percentage, not long term growth. They'd rather swerve their stroke to make balls than commit to a straight stroke.
If you always commit to a straight stroke, noting when you over cut or under cut shots will help refine your aim by instinct.