While I agree that statistically that you will make more five footers than seven, there is no way I would agree that a partial swing is as accurate distance wise as a full swing. This is proven every day on tour that pros don't lay up to awkward yardages. If the theory that the closer you are, the closer you hit it were true, no pro would ever lay up on a par five, EVER.
Really, then why does a PGA tour players GIR percentage drop when they increase their yardage from 75 yards to 100 yards?
Wrong again. Its that the have poor technique, it is about guessing. If a player has proper technique they can develop distance control. With out it, they are guessing, but it isn't because of the size of the swing. Its due to lack of quality contact. So they are not guessing on distance control, they are guessing because their contact fluctuates. They wonder why sometimes the same swing length produces two different shot lengths.