I have the impression that the taste becomes more and more important while growing up, so ds eats more what he likes now and self regulates less that when he was 1 or 2 yo. But still, now he spends periods of eating less and periods in which he eats loads (like now...). And still, when he is given something he likes like chocolate or chips (especially from ILs that give him all sort of junk food...there's no way I can explain them that it is ok, for me, to give him a little chocolate but it is not ok to give him chocolate AND chips AND cookies, all in the same day...) he eats some of them and then he stops, like he has enough.
You have ot do what you feel, but probably a dietician could estimate, from what he eats, if the amount of calcium is enough or not, as pp said. I think the amount needed depends also from the vit D, which is built by our body in response to light and sun, so spending days outside, when the weather is good, helps calcium utilization. And during the summer we have more vit D than in the winter.