I am currently working at a US based airline, Continental Micronesia, flying solely scheduled international ops. US FAR 121 limits us to a max scheduled workday of 10 hours, with 8 hrs rest rqd before returning to work. There are 5 of us, with 1 person on duty 24/7/365. We work day 0600-1400L, swing 1400-2200L and graveyard shifts 2200-0600L on the following rotation-
4 graveyard shifts with 2 days off, 4 swing shifts with 2 days off and 4 day shifts with 4 days off. This was the shift schedule for the wide-body desk at Hawaiian Airlines when our Director worked there.
If you work in the US at a FAR 121 Supplemental airline, primarily freight operations but also charter pax ops, the 10 hour limitation does not apply. At a previous employer who operated under 121 Supplemental, our initial sked was 4 on 3 off 3 on 4 off with 12 hour shifts. As we did very little work on the week-ends, I was eventually able to get my coworkers to go 7 on 7 off. By US work rules, we did not get paid ot unless we worked extra shifts for vacation, sick call, etc.
At another previous employer, World Airways, we worked 4 on 4 off 8 hour days under our contract. We had 1 person for each of 3 shifts and a vac/relief person, on each side of the week.