I decided to go with 2 eyes open all the time for one very simple reason: One less function to control in a critical situation. There are so many things going on in one's brain, so much critical input, during an event in which one's life is in danger, that I don't want to have to close an eye to get off a shot. I always shoot with 2 eyes open.
That's true for my shotgun shooting, too.
.45acp, .40 S&W, 9mm, .38 Spl, .380 acp, 22lr
12 gauge, .223/5.56x45mm, 30-30 Winchester
2 Chron. 7:14 Christians must seek His face