I am obviously making an educated guess based on experience here, however I believe that answer to why the stress is high is what causes reduced code quality rather than the stress itself.

For example, if you're under the pump and have unrealistic deadlines, you are more likely going to write less quality code. Not because you're trying to cut corners, but because when you have the time, you go over your code an improve it about five times before submitting it and have a freer mind to do that.

What are your thoughts?