Matt, this is a good thread and a good learning technique.
In pool there are three main variables on each shot: Aim, tip position, and swing speed. The problem many people have is that all three are bouncing around like the 7s on a slot machine. They feel their aim is right, then they wiggle their tip around, warm up their stroke, now their aim is off, etc. They are swaying around like they are on an ocean vessel, with the shot coming in and out of focus. Then when they feel everything is ok they hurry up and shoot before they lose the feeling. Not ideal.
Best is to break the shot down into two steps. 1) Lock in the aim and tip position, 2) Deliver the stroke. Once you are on step two you are no longer trying to pocket the ball. You are no longer trying to play position. The success of your pocketing or position was determined in the 'aim/tip' step. Now we are just delivering a good stroke to find out if we did step 1 correctly. If you didn't you can't make up for it by jerking or steering the stroke. Just deliver a smooth stroke and if it doesn't work then you learn for the future.
Incidentally the pause when your tip is at the cue ball BEFORE the final backswing is when we shift from 1 to 2. That is when we commit to feeling the shot and focusing on just delivering a swing.
So for people who are learning to smooth out their stroke delvier and segregate their shots in this way there is a lot of value in practicing eyes closed. It forces you to commit to the shot and aim. It forces you to stay smooth because you HAVE TO.
I think it's eye opening to realize you can run tables this way. I broke and ran a 10 ball rack to the 10 ball the other day and then dogged it. I played a student of mine a few racks like this. I'd never broken that way before. Both of my breaks my cue ball stuck perfectly, something I struggle to do with my eyes open. Hmmm. I learned something. Maybe I've been using too much force or too much body movement without knowing it? So yes, it is educational to discover how much feel and locking the image of the shot in your mind is essential. I have also learned how to tap the floor with my cue with my eyes closed, reset it on my bridge hand, and pocket the shot. Some of the time anyway, I'm about 50% and climbing on this one.
Now, once you learn this lesson I don't think you need to keep practicing this way. I played eyes closed for a week once about 10 years ago. When I opened my eyes again I thought I'd play great. Instead my eye patterns were all screwed up and it almost sharked me because I didn't know where to look. So I don't think it's a long term practice technique. But for people that want to do a periodic check to make sure they are locking in their aim and tip, then delivering a good stroke, this is the most effective test I've seen.
I hope folks don’t misconstrue what I wrote. Shooting at a pool ball with your eyes closed does measure your stroke.
But it only works with straight in shots where your cue should travel straight and perpendicular to the pool table. A
steady straight straight is required and pocketing the ball makes your feel good. Your stroke has to be true to pocket
the OB. It is like a golfer practicing a straight putt closing their eyes on the putting green. It offers feedback. But when
you miss, and everyone does, you don’t know what actually happened aside from deducing it afterward. It is useful to
make you feel better bu5 it does not improve your stroke. It gives you feedback about your stroke. The only way your
stroke gets better is by practice that requires open eyes. Your stroke is a combination of your aim, stroke delivery that
involves energy and cue tip contact. To master it, or at least try, needs your full attention and concentration. Shooting
at OB with your eyes closed teaches you nothing. It only offers feedback and I submit that it is incomplete at its best.
My point is there are much more useful, helpful drills, or practice approaches, that will improve your stroke whereas
shooting with your eyes closed does not. It looks good, even feels good but it does not help improve your pool stroke.
Just my opinion, and I even do this occasionally but it’s more for my ego, or self satisfaction. As a practice tool, I think
it is a waste of a player’s time because you don’t learn how to improve shooting with your eyes closed at object balls.
Everyone chooses how to practice & so by all means, stick with what you thinks works best. Open eyes usually helps.