I'm planning to host one every month up until the release of 2.1

[Azgarde]

Since people love to use WoW as an example I do too
Yes somtimes it had content updates 2 month apart. But those were occasions and not the norm. More often than not stuff is/was around 5month after the last.

Although Blizzard releases their expansion with a lot of things to do, that will at least keep us occupied for more than 3 weeks. And even Molten Core, their very first raid back in 2004, had way more bosses than Coils. So there's no way a re-released game would have only 4 bosses for 6 months.