I'm not sure I agree with this. Granted good design takes some extra work. But for the most part, in my experience, coders who write bad code also do it slowl

I'm not sure I agree with this. Granted good design takes some extra work. But for the most part, in my experience, coders who write bad code also do it slowly (perhaps because they don't understand it), while those who write cleaning code are able to move more quickly. As a project grows, you have to refer back to your own work more often. The price for poor code starts to be paid almost as soon as the cursor leaves the page.