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.