About 4 years ago I setup some shots and had my wife shoot using traditional ghostball guesstimations, then had her shoot the same shots, which were 1/2 ball and 3/4 ball shots, telling her to aim straight through ccb to the ob edge or halfway between ob center and ob edge. She was a D player, but would occasionally be able to pocket 3 or 4 shots in a row.
We started with straight in shots just to make sure I had the cb close enough to the ob to minimize wonky stroke errors. The distance was about 8 to 10 inches, and the ob was about 25 inches from the pocket. I think she shot a total of 130 shots. The results proved without a doubt that knowing exactly where to aim, compared to guessing or estimating where to aim, can drastically increase pocketing percentage.
If I had set the shots up with 2 or 3 feet between cb and ob, the results would've been inclusive because her inconsistent cue delivery/mechanics would have influenced the aiming experiment, and I wanted to minimize that element of her shooting in order to highlight the difference between aiming methods -- the difference between knowing where to aim and guessing or estimating where to aim.
The same theory can work to highlight inconsistent stroke mechanics by simply increasing the distance between the balls and using a known aim point to pocket each shot. If the aim line is 100% known, and you shoot the shot 20 times, pocketing the ob cleanly each time, then your stroke is fine. If you miss some of the shots that would indicate a stroke error or an alignment or visual error.
Let's say you pocket 50 balls in a row, each shot being a halfball aim. That would prove that you have a good stroke and alignment to strike the cb along a known path. Next you randomly roll the cb and ob out to a shot, ensuring that the distance between cb and ob is about what it was on the 50 shots you just finished, then shoot the ball based on where you think or feel or estimate the aim to be. Do this 50 times, 50 random shots anywhere from straight in to about a quarter ball hit. Don't setup world beater cut shots or bank shots...keep it simple.
If you make all 50 then you have excellent stroke mechanics and excellent aiming skills. But if you miss a few, or miss a bunch, it would indicate an error in aiming skills/judgment. Your feel/estimation/guessing isn't the best. You'll have to put in a lot more table time. Or you can adopt an aiming system or method that will help you recognize certain shots with more regularity.
