I've heard for many years that shooting with both eyes open is the "best" way to do it. It may very well be, but I simply cannot do it.
50+ years of shooting rifles, pistols and shotguns with my left eye closed has created a "muscle memory" or habit, call it what you will, that I simply have not been able to break with any degree of success.
Put quite simply, when I shoot with one eye, I HIT what I aim at, when I use both eyes I often do not. Right or wrong technique in the eyes of a trainer, I'll stick with what works for me, no matter what they say.
After all, what its all really about is what works, for you. There are methods that work well for most people. There are methods that work well if you begin your shooting training using them and become ingrained, so learning to use a different method is more difficult because you have to unlearn then learn.
I was once nearly forced into such a situation, in Basic Training. I shoot a rifle the way my father taught me. When I'm not using it for support, my right elbow is up in the air, not tucked down against my body. (and, I had a decade of shooting skill using this form, before I went into the Army)
One of the Drill Sgts began to get on my case about it, because my style was not what they were teaching everyone. A barked "WHO taught you to shoot that way TRAINEE?????" My answer "My Father, Drill SGT!!!!" clearly did not make him happy, and it was clear he was winding up for a rant that would end with me doing pushups and having to use the position exactly as they taught it.
Then, to my surprise, one of the other Drill Sgts showed him one of my targets. Group size was half the size of anyone else in my platoon, and only two other guys in my COMPANY matched, or beat it.
The Drill Sgt who spotted my "mistake" grunted, paused for a moment, then said, "well then keep it up!" and went on to make life miserable for another trainee.
The old saying "if its stupid but it works, its not stupid" isn't completely false. It doesn't have to be stupid, if it works for you (or for me) then it works.
Another method may be better, more efficient, more effective, maybe, but if you can't get there, if it doesn't work, for you, then its not better, for you.