Rabbit123, I can see where you're coming from but I think that they relied on overtime to overcome the staff shortages in the misguided belief that the next airspace change would resolve the staffing problems. All the controllers on the floor knew this not to be the case but noone asked them, and surprise surprise, the usual outcome from these airspace changes and reshuffles of sectors has been a need for more controllers not less.
Now that the crunch has come, they are trying to recruit from overseas only to find the shortage of controllers worldwide means they are in fierce competition with other ANS providers.