Pardon me for the long post, here is the exciting conclusion:

I keep score on every shot as if I were at a match and try to duplicate the stress of shooting under pressure. I have also found that extraneous thoughts during the aiming process are the kiss of death. Not sure how to get rid of them, but I am working on it. 
I do not tighten my grip until the sights are settling down in the bullseye, and only maintain that grip for a second or two until the shot is fired. 
The point at which you should let the shot go depends on your comfort level with your amount of wobble. Hopefully, as your wobble area gets smaller over time, you will know what is right for you. Taking a swing at the bullseye as it passes through the sights never works for me, I need to have it move very slowly more or less centered on the bullseye. You have to develop or maintain a quick reaction time, which gets harder for me as I get older, at the same time not developing a jerk or disrupting the sights as you touch off the shot. Follow through is key here also, a good hold with poor follow through will ruin a good shot. 

This has been a process for me which is constantly evolving as I learn from the great advice of fellow shooters and my own experience. I hope it helps you out. 
Joe S

Kind words from Chris, the best shooter I’ve ever known, and good advice from Westerner. 

Once a shooter has all the basics to the point they are automatic the only thing that’s important is target focus. Putting the bullet on the exact spot . It’s the same with all shooting sports, some examples.

Most difficult shotgun sport is Sporting clays. Wide variance in targets  path and distance 100 shot matches two in the air at a time 50 presentations.  Best shot ever George Digweed uses the tightest chokes possible even on very close targets. His reason  is target focus, shifting to open chokes knowing wide pattern makes it easier would make him sloppy. Better to focus hard and not rely on wide patterns to break the target.

Steel Challenge another it’s shot 4 classes Rim and Center Fire Rifle and pistol, all standing.   100 shot match 20 5 target strings scored by time required to hit 5. 10 shot magazines 200 shots allowed you can re-shoot a miss but go back and re shoot one adds time. 2 seconds minimum more if  it its takes multiple to hit.
Target size distance and placement varies shooter plans the speed and sequence. Only requirement ones painted yellow and stops the clock when struck.

The key to time and winning is plan were you want the bullet to strike, fast on large targets slow down and be sure on small and don’t  miss the yellow stop plate. Only way to do well is move the gun smooth target to target and pull the trigger as the sight acquires the desired spot. You can’t count on reshooting misses hitting all first shot is critical.

The guns are very accurate ones my grandson and I use are Ruger 10/22’s. His much modified stock and trigger mine from the Ruger custom shop improved compared to regular Barrel Trigger and stock. Both use red dot sights no magnification with varying quick change dot size shape and intensity 

Few months ago I was practicing on our club Single shot rim fire Ram Bash course 75 yards, with my iron sight CPA. When I was younger and eyesight was better 90 % hits my long run average. 9 out of 10. Now 80 % more like it. Had the Ruger in the car. Didn’t want to change the red dots zero figured top of the rams back gave center body hits.  The first run 10 hits, next same 10, third 9 hits. Forth 10 score 39 this going slow target to target Ram Bash pace not Steel challenge speed 

Ruger had a higher hit % shot placement due to the sight and shooter placing the bullet not the gun.

Boats

Relax yer arse and practice.....

Water we got.  At least on the west side of the state.  We have a rainforest in the northwest on the Olympic Peninsula.

My definition  of "Hard Hold", is holding for center and not moving in from the side, top or bottom. Just point the sights at the bull and shoot for center. If your grouping low, move the sights up.

I might add that you need to relax your body as much as possible and not bend your neck, either.

Let the rifle come to you, not bend yourself up to fit the rifle. 

I learned everything that I can't do, from a very good High Power shooter, that helped me start my club.

"Somes got it and somes don't". 

Very few do in this sport that was founded by manly OH shooters. When I started, in the '80's, there were at least 20, OH shooters that could average 220 scores or close to it. I don't know of anyone that can do that now.

I'm no good at OH but, I would like to see that kind of shooting again.

This might be interesting:

I started my club in '86 with that High Power shooter I spoke of, John Haas and he was best friends with with Richard Corbin of bullet swaging fame. He and his bro, Dave were still together at the time.

Richard was the best OH, HP shooter on the West Coast at the time. John got him to shoot a SS in practice once and I got to talk to him. I ask about why he thought that he shot well and I wasn't expecting the answer he gave. He said that he could "will" the rifle to hold, long enough to get the shot off.

I tried hard to get him to join the club and shoot with us, I even offered a rifle and ammo for him. But, he was getting married and had lost interest in shooting.