In the US all facilities do it a little different to accomadate traffic. But in the enroute environment we staff slightly lower on the day shift, higher on the evening shift and then down to minimums on the midnight shift. The area that I work in we normally staff anywhere from 10 to 12 people on the day shift. 11 to 13 on the evening shift and then 3 on the midnight shift. We have 6 sectors that we can work. Four of them are full time open sectors for the day and evening shift, and two of them are part time... On the midnight shift we only have two sectors open.
All that said, we quite often go down to 9 or 10 people on the day and evening shifts when we are short handed due to vacation and sick leave. You normally have to go below this to get someone to call in overtime...
Again, this is ONE area in our seven areas in our center. Everyone has slightly different numbers. It is that way all over the US...
regards
Scott
PS. No one goes home on official time for the midnight shift. You are there for the duration unless you go home sick, and then you work with two people...