system
A chat on subreddit /r/NoStupidQuestions
human
Some people do, but I'm not sure of the numbers. I don't think it's many that work 12hour shifts.  For example, I have a friend that works 3 days in a row, 7-7.  Then she has 4 days off.  She's a nurse in a surgical unit. 

But most other people I know either work 10 hour days, 4 days a week, having 3 days off, or the work 5 days a week for 8 hours.
gpt
Or you work hvacr and work the 7-7  7 days a week when you’re on call.