> When you find out that the architecture is wrong, do you fix it? Or do you just hack it to get the next bit to work?

That's very project and organization dependent. Some projects are short lived prototypes (I'm working on one now) that are for internal use only, so it makes sense to try and get the damn thing finished without worrying too much about architecture.

Other projects are built to last, or have very high quality requirements, so you want to really get the architecture right, even if that means costly rewrites.