Ensure and children. For a 13 year old to drink ensure every day there has to be a reason. Is the child a poor eater, or has health issues and not gaining weight or just lazy not to eat regular meals. If the child has health issues & not gaining weight it is okay to do so. It is otherwise better to sit down and enjoy your food in its natural form!
Ok, yes; smart? You can get approximately the same nutritional supplement value out of packets of Carnation's Breakfast essentials added to milk or almond milk. This would cost a fraction of the other. Some kids can benefit from these products, but for some it is unnecessary and may alter their appetite for normal meals.