You know talking about the two starts…
The two start layout at Disney was born not of crowd control, rather two race starts. In the early years, the left start was the half start while the right start was the full. Then as the races grew, specifically the half, runners were mixed half and full based on times with the right side being for the faster runners and the slower runners on the left. That did not work well as the wheels will zip through the first lap before the left side clears mile 1. In 2006 when the half was moved to Saturday, the corral seeding was unique for the full. The left side went corrals A, C, E and the right B, D, F, G, H… that failed to work well so the format of the last four years; three fastest on the left and the remainder on the right was run.
I am looking forward to the new start format. I think that it will open up the course so that the crazy merge point issue will finally go away. I will hold judgment on the next pinch point at mile 5; but I will bet it is not as bad for most runners, also.