The story is the quick bit. Exceptional graphics is what takes time... Full stop.
Yeah, and by exceptional graphics, it's not even the actual
rendering that's so time-consuming. It's everything behind the render: posing, lighting, filling up the background, small expressions - and then redoing that over and over for each render.
Ocean's greatest strength is also his greatest weakness: he's a perfectionist. You'll never catch some character's fingers in the background clipping into their body; he's going over each render with a fine-toothed comb. The trade-off of this, is of course, time. Personally I don't mind a bit of imperfections if the updates come faster from a dev, but that's me.