Well, imagine yourself working 12 hours a day constantly in a sitting position, crouched, trying to make 20 pages done in a week, all the while trying to keep the story and art consistent.I swear I knew it was coming, anytime something intense happens mangas seem to go on break. I swear as soon as I saw the bankai I was like "Damn...it's gonna be 2 weeks at the minimum before we see the conclusion of this here" I hate being right sometimes...
Aizen lookalike?^
or maybe the aizen-look-alike didn't want Urahara to pwn him, so he poisoned Kubo to prevent it from happening!