My experience is that it is very common for cooks not to get breaks even on 16 hour days. I can even remember when i was 18 pretending to go to the bathroom just to get out of the kitchen
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Even worse than not getting a break is cooking family/staff meal while the waitstaff/FOH managers eats it and we get to keep plugging away n the kitchen while they enjoy our cuisine. Maybe we get a bite out of the pan when they return a hour later as its lying on the dish table,.
Just my experience