Is 3 cups of hard food enough for a 70 pound (Husky mix) ?

The bag says 3 1/2- 4 cups but I've heard that the bag usually recommends too much. I was just wondering if anyone else has a dog that size and can chime in. He also gets treats too everyday.

I will add that he poops often(Sometimes twice a day) so I figured that was a sign he might be eating enough.