As soon as the player learns to keep their eyes and head still when putting, they will begin to make more putts!
Developing your putting routine to include keeping your eyes and head still when putting avoids swing path and clubface mistakes. If you do nothing else, keeping still when putting will increase your percentage of successful putting strokes which means lower scores. Get in the habit of holding your finish when the stroke is done so that when you look, you can check the position of the putter face. On short putts, the face of the putter should still be pointed at the target.