BE says in his book “If you can’t keep your eyes open when you shoot, there’s honestly not much you can accomplish until that ability is acquired.”
So, the trick is how to keep the eyes open.
For me it is the same old solution is “dry-fire” but that is a lame answer that isn’t specific enough. It’s just like asking what it takes to fix a car and saying “tools”.
The “white wall” drill is the first on my list. Aim at a blank wall and watch the light on either side of the post and pay really close attention to what is happening to the sights. All concentration on what the sights are doing.
Then there is group shooting. Watching what the sights do for at least three shots at a time. I usually do this at a distance where I can’t easily see the holes so I’m not tempted to check what I am doing.
Up to now this helps slow fire. Not blinking to track the sights is more important with faster splits.
Bill drills into the berm helps analyze my grip. I have what I expect the sights to do and what actually happens. I start off with two shots then three. The final test is six shots.
I almost becomes unnecessary to do it on paper to know that I’m not blinking. However, Bill drills at different distances gives information on proper tempo and necessary sight picture to hit alphas but I consider this different skill.