"speed in focus being what causes eye dominance"
Sorry, but nothing could be further from the truth. Plus, a little beyond a meter or so the human eye is already biologically and physiologically focused for distant objects. This assumes normal (corrected or otherwise) vision. We cannot purposely "focus" in on distant objects, our eyes automatically do it for us. We can peer intently, concentrate on, etc these distant objects such as birds or clays. We CAN, however, purposely focus on near objects until presbyopia sets in at around 50 years of age. To put this simply, our accommodative ability (the ability of the eye to change focus) diminishes with age. When our eyes are in a relaxed state (no muscle tension on the lens) they are optically focused for distant vision. Some of the vision stuff I have seen put out by supposedly knowledgeable shooting instructors is absolutely false.
