I get a sense he might've pulled another Claymore. After it was over he revealed he gave up planning ahead pretty quickly on it (he expected the axe after the first or second arc) and just kind of spitballed where to go next as it came to him. Volume after volume, the axe never arrived so by the time he got to a point he felt was "the end" he found himself having to corral all those ideas back into something unified.
Is there confirmation on that?
Well, regardless, with Claymore the corralling was done in such a way that it really did wrap up
naturally.
The overarching plots of the treacherous organization, the various monster and hunter personalities, the mystery of the Yoma, and the epic battle between the heroine and main bad were resolved. Even the wrapping up of the organization/yoma mystery
before the main battle was done in a way that helped resolve and move forward the plot to the suitable climax.
This was...definitely axed or rushed in a very painful way. I'm feeling axed. There were too many ideas that weren't resolved in a remotely sensible or satisfying way to explain it.
I liked the story, but sprawling stories like this only really feel good when they have an ending that pulls together the major threads, resolves them in a fulfilling manner, and leaves tantalizing bits of the unfinished ones.