Often factories want to get the maximum use out of their equipment since it's very expensive and only lasts some finite number of years. Many factories run 24 hours a day in rotating shifts to minimize the downtime of their machinery.
I used to work EMS 12 hour shifts 6-6. At one point management decided to stagger base start times. Some 6-6, others 7-7 & 8-8. So when someone flips their car and flies out at 5:45 they don’t have to wait for all the available service to finish their shift change, when the 8-8 team has 2 hours left they can get to the patient and back to base without extending their duty day too far.
Many of the workers who went 8-8 hated it. They complained nonstop about how it ruined their whole day since day shift they are headed out the door before the fam eats breakfast and get home after dinner. Same for night shift, rush through dinner or miss dinner and breakfast with the family.
Personally I enjoyed the 7-7/8-8 shifts more but enough people bitched enough they changed all but 1 base back to 6-6.
Huh. So it seems to me that when the job requires 12 hour shifts, the employees require at least one meal with their family, and the most common solution is to start early enough to let the employees make it home for dinner.
Yeah, not sure if I answered your question in regards to what you were thinking about but this specific scenario the 6am start time worked better for many of those with families.
It’s like that for the most medical communities. Some nurses and docs spend a full week at the hospital. We were an air ambulance so the FAA limited us to 12 hour shifts but many ambulance, fire fighters etc. are 24-72 hour shifts.