Last year Marathon had a red and blue start--and they merged after going through EPCOT.
So their lag time from start to last runner crossing the start is much less than the half since they are split up into two separate areas. Though corrals are unique.
The half was TWICE as long in the corral as they had us all lined up one after the other.
I was in the next to last corral with hubby (he put a slower time)--we still finished in 2:38--lots of zigging and zagging and we were about 17:00 to the start..so still under 3 hours WITH the low corral start.