The way our NOC does it is:
- alternating between 3 and 4 days per week
- 12 hours per day
- two people per shift
This makes for an average of 42 hours per week and a four shifts of
two people, or a staff of eight. Keeping a ringer in the rotation is
probably not a bad idea either, and of course fnord! a manager is needed,
bringing the total to ten. This is not my department, so I'm not the
expert I pretend to be.