[Mr. G36!]

I do it all the time. I use both eyes when scanning, and when I see an enemy, I close my Left Eye so that I can center the Dot in my Reflex RDS properly, since I find it harder to do if both Eyes are open. But I've always dine it that way, so it may be an acquired skill. I've never found it to waste time because you're already aiming while closing your Left Eye, and by the time it's fully closed, you've already fired a few BBs, and less than a second passes during that full motion. Just experiment with different techniques out there and you'll find something that works for you eventually.