Just from a judge's point of view and I can only relate to what I have judged and from what I have heard from fellow judges (yes discussion DO take place in private).
A horse exibiting correct movement within the level competing at (assuming nothing else is taken into consideration) should get an automatic 5. What increases that mark will be animation, presence, mettle, and correctness of the actual movement. A horse that has an extraordinary large ground covering movement will have difficulty in collecting so the horse that has say better than average (but not extraordinary) movement will usually do better in those collected movements. What Allison was referring to will show up as obedience and presence and becomes part of the whole package (but also in the collective marks at the bottom of the test).
Many times an average moving horse succeeds at the higher levels even if they have been beaten by the horse with the huge movement.
Reminds me of a friend that had such a horse. Beautiful movement. One test they did a breathtaking extended trot across the diagonal.................however you are
supposed to stop when you reach the fence at the other side.................oopps. The horse that won was a very nice horse,very obedient and went on to do GP. My friends horse never went past medium.