I asked the question because I was having quite a few consistency problems with fats and thins no matter where I focus on just the moment before I move my club back.(in front of the ball, on specific places on the ball, inside of the ball etc.)
Then it darns on me that if I want to chop something with accuracy down to millimeters with a knife, I would like to know where the knife edge is before I lift the knife. So, I experimented (after all the usual alignment stuff) with looking at the bottom edge of the club face just before I move my club back, then the rest of the time on specific points on the ball. My consistency went way up and hitting the ball solid with this subtle change.
I think if I concentrate on looking at the ball, I have lost my reference of the club head momentary and that makes a big difference.