That may hold true for cage birds, but I've seen poultry die on the nest from brooding for too long. Silkies are notorious for that, but other breeds of poultry/game birds will do it too. Unlike finches and other cage birds, poultry and game birds do not have mates that will feed them enough to survive and/or thrive on.
My button cock brings food to the sitting hen, is this unusual?
He will bring her crumbles or mealworms until she is stuffed.