This probably does not help, but...

I used to love that automated categories and had 4 categories. One day I suddenly felt that that was too many and reduced it to two, "Primary" and "Updates" (similar to mail.live.com's "focused" and "other") and found it actually easier to manage my emails. Of course that is still two not one, but just want to say that you might also realize that you don't need so many categories.