The issue is probably that when you split it by just asking for the next section, you're asking it to figure out how to continue from a block that wasn't written with the awareness that it'd have to add on to it.
From the diagram on the repo, I guess this first plans out the structure for each block, and generates the blocks based on the plan.
Like, not only can it not “make a complete app in 45 seconds,” I almost never even want that.
With editing or lots of regeneration it can still work, of course.
(That said, I last tried this with the original ChatGPT…)