But it's an interesting idea that "eyes on the CB" players then shift to look at the OB immediately after tip contact. That kind of 'immediately after' head movement (assuming the head moves) would have to be a risk for bleeding over into head movement during the stroke. Do "eyes on the CB" players tend to move during the stroke? I guess you'd have to study some to check.
your head doesnt have to move as you switch from looking at CB to looking at OB, well some do. It all depends on your pattern/style, alot of people have different styles.
You can do your eye/aim pattern by just moving your eye balls while your head is fixed in location, i.e. you can have this looking at cb/tip then into the OB, then back to cb/tip, then back to the OB, then within the final stroke your eye will look at the CB as it hits it then immediately go to the OB as the CB is moving towards it then your eye will also look at the pocket after CB/OB contact.
The eye pattern is different from person to person but we all share this last thing that I said upon hitting the CB you will see the CB then immediately the OB, this is a rule and you can check all pro players about this, you'll see that Iam right.
Now about the head movement it depends on the style as I said previously here, and ill give you examples.
Style #1, Head is still and fixed, the eye-ball is the one that moves (Most pro's)
Style #2, Head is fixed but eye-ball moves with the eye-brow, often you will see this player eye-brow goes up and down as he do the pattern, and in the last stroke you can see his eye-brow clearly doing exactly what I describe, as he hit the CB his eye brow is down, and in the moment of impact his eye brow moves up (Looking at the object ball here). --- Example Jushua filler and many others do this, I think Ralf Souqet also does this.
Style #3 - The whole head moves up and down, it is similar to previous case but this time its not the eyebrow + the eyeball, here in this case his whole head moves slightly and slowly up and down with his aiming pattern, this movement still is accurate as he does the same exact thing, his aiming pattern and then in the final stroke again as I said before but this time its with his whole dead. (Example David Alcaide).
You can check what I said all on youtube, just observe. And remember this, do not ask them! as they often don't know, its all automatic to them. So just watch it yourself is better than asking them.