Umm actually, they do. American football players use narrower goals for practice so when they see the upright it's a much larger goal (meaning less chance to miss), as evidenced by the Denver Post (and just outright googling):
https://www.denverpost.com/2009/12/31/some-kickers-using-narrower-goal-posts-at-practice/
In soccer, they often reduce goal size during practice to reward precision. Also, "Smaller goals mean smaller targets, and if you can aim small, you’ll miss small when it’s game time. Practice hitting a small net every time, and suddenly that regulation soccer goal will seem like a wide open target." That's from Rukket Sports Guide to Soccer Training Tools:
https://www.rukket.com/blogs/news/a-guide-to-soccer-training-tools
In basketball, players often practice with an undersized hoop in order to become more accurate as well.
Did you even research anything you said in your post mikemosconi, or did it just sound good? Sounds like your blood pressure is just high thinking of your error rate with the large, loose, regular-sized pockets and how higher it will go trying to get to another level using reducers. I am with Earl Strickland when he asked for tighter pockets at tournaments, making things more difficult for the people at the "top of their game".
But the idea is the same. You have smaller pockets while pocketing balls, which builds muscle memory and accuracy (as well as concentration and CONFIDENCE) so when you play someone on a regular table, your brain has super confidence seeing how huge the pocket is now.
But each their own. This may not work for your brain or way of learning, and only be a hinderance. Stick to what works for you.
