I think something like pillar of unity should be permanent( add new floors every so often). This way guilds always have something to work together, and not just in a few days. Especially for people with lower guilds or no guilds.
By being permanent, there is no rush and you can see a sense of progression as a guild starting off slowly climbing.
Like I really like the idea that the more you do a stage it gets weaker, I can see this being very helpful when helping lower members. But since its an event, most people just spam the newest one as much as possible.