Killington's Canyon has the black East Fall leading to all double black.
Um, no it doesn't. Lower East Fall leads right to the chair or Spillway. You don't have to ski double blacks after skiing East Fall, in fact it's not an option at all. Same thing with Royal Flush. Killington is actually pretty good about making sure people don't end up on terrain that might be above their ability level. Spacewalk used to be a Blue Square years ago and is now a Double Black because the only options it leads to are Outer Limits and Devil's Fiddle.