I use the 8-10inch target, and make use of it at the range as well, because I think it takes a while to develop confidence in the method. At the range, I will place a small piece of gravel a foot in front of the ball, in a line with the target. I also place a club six inches outside of the ball in line with the target, because at the range, I tend to align myself to the edge of the mat or bay, so this helps with my stance as I move the target around.
The advantage of this method, is that it helps to free your mind of swing thoughts and makes you more target aware. On the course, you are so busy concentrating on the near target, that negative thoughts about water, trees and other hazards just don't come into the equation.