Very long time for all of them, yes, but marginal employees can be reduced through automation fairly quickly. Go from 3 people to 2 at a restaurant by using more pre-cooked food or automation, buy a better PoS/order management system to remove one waiter from front of house, etc.

You don't even need to fire anyone -- just hire more slowly than otherwise when things are growing, and potentially not replace people when they leave (although that's less scheduled).

Quite a while like a decade or two? That's not that long for the end of labor, a 10,000+ year human institution.