I'm of two opinions on the matter. The first is that my free time and my sanity is worth far more than any job could hope to pay. If I'm being constantly overworked or in a working environment that is a major source of stress and can't come to a good resolution, I have the means and the will to do something else. My standard of living is modest, and my skills are good enough that I can get by.

The other approach is a pragmatic code-warrior approach. Though I tend to overdesign things (like a good free software hacker, I believe in too much flexibility), there's definitely a place for getting things done quickly and not adding more features than you can handle.

There are even a couple of schools of thought in computer science that encourage this approach. One is refactoring, and the other is Extreme Programming. Fred Brooks said, roughly, "Plan to throw one away. You will anyway."

Of course, if deadlines are short, you may not have time to refactor your code or throw away legacy stuff, and you'll be left with a hard-to-maintain pile of proof-of-concept.

There's nothing like going through a nasty subroutine and cutting out half of it while making it run faster or use less memory -- but there's also nothing like going in to a well-designed module, pinpointing the bug, and fixing it without having to sift through the call stack for half an hour.

If you pressed me, I would suggest that you err on the side of clean code and good discipline -- if you clean up after yourself now, you won't have to dig yourself out of it next time. And there's almost always a next time.