Every Blue Orb you use today is 2-3 months of waiting on Zuul’goth when you decide to use it.
ZG isn’t useless like it used to be. There are a few teams where it is devastating if you don’t Rope Dart your way to destruction before it gets going. I can’t think of a troop where ascension to mythic represents as big a boost as “getting a troop you don’t have” does.