Why did they pick 4pm? In Seattle, for example, leaving at 4pm frequently means you miss heavy traffic all together while leaving at 5pm is almost a guarantee

Why did they pick 4pm? In Seattle, for example, leaving at 4pm frequently means you miss heavy traffic all together while leaving at 5pm is almost a guarantee of gridlock the second you get on the freeway. If you leave at 4pm and head due east on 90, most likely you'll be in eastern washington by 5pm and won't hit any traffic at all. In SF it is more complicated because there are big traffic problems in almost every direction so if you leave at 4pm and are still driving somewhere at 5pm, then you'll get stuck in traffic. Still 4pm seems like an odd time to pick.