So modern data from computer analysis, and the SAM putting lab and the data that comes back from these things shows us that when you putt the putter face and the direction the putter face is aiming is 85 percent responsible for the initial start direction of that putt. So the path of the putt is important to a degree, but it is only 15 percent of the initial start direction, 85 percent is controlled by that club face. So if we could do an exercise to make sure that the club face is actually square as you hit the putt that would be a good thing.
Use Tee Drill for Square Impact with Putter (Video) - by Pete Styles