I had an article due this morning. Yesterday afternoon got away from me for various reasons, and I don't write well (don't do anything well) in those first hours I'm awake. So I sat down at 2 am to write, crawling into bed at 4:30, sending the article before I did. I had nothing on my calendar and no boss to answer to, so I could get real sleep.
Editor emailed me at 8:30 to say she thought I did an excellent job and offered me another assignment. I really enjoy working for this magazine and editor, too.
I love being able to work when I'm most productive and not during an artificially set "work day" standard.