Tom,
I understand the distinction and motivation for your method. I will say, although they probably won't say it, it drives contractors crazy, specifically in that their contract still makes them liable for completion dates, etc., and they can be at the mercy of independent shapers. One gca's contract for the same method specifies his guys can take a vacay at any time, including during the final push, which hardly seems fair to the general contractor. Generally, I favor the single point of responsibility be with the contractor.
I have seen few instances where the profit motive has really kept shaping changes back. I actually have a "yards, feet, inches" clause in the shaping section, recognizing that I have the right to major changes (moving a green several yards, if necessary) but after that, changes have to keep getting incrementally smaller. I think that isn't too much to ask an architect, to make up his mind at some point, LOL.
The most trouble I have with independent project foreman or shapers is simply clash of egos or passive aggressive personalities. Every so often, you run into one that would prefer to build almost anything other than what I have drawn and modified. Tough line to follow, because every so often, the shapers come up with an idea I would have never thought of and improve the project greatly. Working with guys who have just come off a Doak, Fazio, Young, or whatever course increase the number of ideas under consideration, which often helps creativity over always working with the same guys.
So, in the end, it comes down to the people, and contracts mean less, but it can go all ways, for sure.