Also, traffic. The first guy in line gets slam dunked, and the last guy gets slowed way early. How often are the winds at 100 knots on the tail when you start the procedure, then a 50-KT crosswind at the approach control boundary? When the front of the line is only going 300 over the ground, the last guy in line going 500 has to slow early and descend into the same wind to hold the required in-trail spacing.