Ribs, salmon, eggs, they are all natural ingredients. Two different fish, two different cows, they will be different. The good chef knows that a medium-rare steak is not 6 mins - even two rib-eye cuts from the same cow will cook different. It will also depend on thickness of cut and temperature you started out with as well.
McDonalds, that's not natural ingredients. But even there, there are good outlets and bad ones. For example, there's a McDonalds near Amir's store that makes the best Angus burgers of any McDonalds I've been to - we'll drive all the way there whenever the kids want a Happy Meal.