Why is it that each arc this series has a separate entry? Rather than just putting it all in one place?
It's so that the author can assign multiple artists work to help tell his story. Rather than one artist/group doing the entire story series (slowing progression), as one story arc is being or nearing release, the next (or previous) story arc is being worked on ahead of time. I've counted at least five different artists for this single author's works.
Admittedly, I wish there was an index that lists each story arc, chronologically.