Usually when a ghost fleet World Event appears, it stays up for quite a long time. I feel like it's less because of them not being fun, but how they take so much longer than other events.
Personally, I think it would really help if we removed the third wave in the World Event. We already had a "general wave" and a "(mini-)boss wave", do we really need another general wave before the "(Burning Blade) boss wave" comes? I feel like reverting a phase just feels tedious, especially to new players who don't know the pattern yet.
Even with just three waves, the event would still be pretty lengthy.
