I think the number was unusually high for this particular race because the out-and-back is at the tail end of the race, is very long (4 miles out, 4 miles back), is only separated by traffic cones (making it easy to cut to the other side), and the weather was unusually brutal (very windy, near-freezing). It never occurred to me to cut to the other side, but I can understand why it did to many others.