I have been on flights (Air France especially) where after the dinner service has finished the whole crew seem to disappear for hours leaving the token one to walk through the cabin section making sure her charges are all asleep and behaving themselves whilst their mate sits in the galley reading a mag. Where did all the others go?
I'm pretty sure that AF, like most other airlines, regulates for 1 FA minimum per galley during rest periods. If this is enough, who can say? In an emergency it becomes precariously few, and to the pax it looks as if we've all disappeared.