and honestly, you probably could have done the job better and faster if you had done 8-10 hours (or less) per day and had enough time to mow your lawn, pay your bills, unwind, etc.
No question about it. Repetitive long hours are deleterious to critical and creative thinking abilities. It always makes me think twice when I see stories about game dev / wall st / startup developers working insane hours. I think the story is better than the reality.