Board Thread:Questions and Answers/@comment-28194879-20160519003219/@comment-5774380-20160519023310

That blog post explains why is the anime season taking so long, but if you ask why the manga releases a chapter every month, the answer would be simply because it's published on Bessatsu Shōnen and that's a monthly magazine.

And I wouldn't take One Piece as an "ideal" example, considering the gross amounts of filler that it has and the huge drop in quality that it experienced after the timeskip. I stopped watching the anime at that point because most episodes were so bad that they made me feel ashamed of watching them. A few weeks ago I watched some of the latest episodes and confirmed with disappointment that the situation hasn't improved. I still follow the manga mostly because it still has some shining moments, but it is far below the quality that it once had.

I don't want the same to happen to AoT, so I'll continue supporting the monthly format. If I'm not mistaken, Isayama's monthly schedule consists of one week of planning and three weeks of drawing, so in any case that's a more comfortable schedule than the same amount of time but split in mandatory releases every week.