The most work hours in a row n a non-dev job were 14 hours, but they were the hardest.
During University I worked in a warehouse once a week. It wasn't that bad and I could rest my brain for 8 hours. But around Christmas time they wanted me to do some extra work (as well as everybody else there). So I had to carry 20kg packages for 14 hours. Three days in a row from 7am to 9pm. I had two travel two hours to work and home again, so I had to get up around 4:30am and went to sleep at midnight. I'm so glad it was only a student job and I don't have to do this in my current job. And I feel sorry for all those warehouse workers, who had to do this regularly.