We have 3 children (ages 11,12,13). They are all on the adult meal plan. Our middle child is a very light eater and also very picky. At every table service meal 4 of us use DDP credits and we pay OOP for the 12 year old. He always eats off the children's menu. With his credits we are able to add two, 2 credit signature dinners. Even at the 2 credit signature dinners we pay OOP for his means off the children's menus.
The only way this doesn't work out is if you are at a dinner show or a buffet. If you take an adult child to a buffet you either have to pay OOP at the adult price or use an adult credit.