Well, for our operation, we have 21 737 flying approx 8 sectors a day.
Shift coverage is one Senior Controller, one controller covering all aspects of ops and crewing.
On the roster, we have five seniors, and five controllers.
There are four rotating shift patterns and two floaters covering leave/courses etc.
There are also three officers who cover earlies/lates whilst dealing with slots/hotac etc.
I say again,this pattern really works for us. I was sceptical at the beginning, but was pleased to be proved wrong.
It may not suit all carriers, but I know its used at a number of UK operators.
And as for the 12 hour shifts? After 15 years, I guess I'm used to it !