How much should Ethan eat?

My ma and cousin got into quite a knot last night. Before they came and fetch him back, my ma suggested that he had a bottle of milk, since the last time he had one was 5pm, and it was 7.30pm then. He had his milk every 3 hours, in my house. Whereas at his place, his folks let him eat only once every 4 hours. Because they went to see a doctor, and the doc said the baby was eating way too much, that he should cut down. So obviously, the parents heed the doc's advice (who doesn't?). But on the other hand, my ma strongly believes that a baby should have a bottle at least 3 times during the day (I agree). But after listening to the doc, the parents only let him eat twice during the daytime, on the weekends when he's not over.

I dunno who to listen to, the modern logic (the doc), or the traditional logic (my ma). You see, milk formula is actually not that filling. It's only powder and water. Liquid food. The baby pees maybe 3 or 4 times, then the bottle of milk is out. He'll be even hungrier if he poops. In my opinion, just let it be lor. He eats less at home, he eats more over here. I just hope nothing bad will result because of this.