Board Thread:Wiki Discussions/@comment-12509038-20140927020530/@comment-23887466-20140928043932

Well, this is a similar case to some previous arcs. Take the Pain Invasion Arc as an example. The arc contain Taka's Attempt to Capture the Eight-Tails as well as the Pain Invasion. Yet we didn't make an arc for Taka's mission because of the number of chapters. While the Chuunin Exam was split between Chuunin Exam and Konoha Invasion because of the number of chapters each arc have.

So the deciding factor will be the number of chapters, I guess.