When I had my feed formulated originally (I got it from a feed mill made without soy), I had them do an "all-flock" level of calcium as I had to purchase so much of it at a time that I couldn't justify getting different formulations 300 lbs at a time when I only had such a small flock. So from the beginning of my having chickens, I've always used the same formula from chick to adult.
The chicks and young birds get more protein by adding other items to their diet and there is always free choice calcium source which is usually just the oyster shell or calcarb in some form available. So far it has worked well.
Something that we often don't take into account is that if they are out foraging during the warmer months, the bugs and other items they get have calcium as well. Since we can't control those levels I still think it's good not to go so high on calcium in the "forced ration" that they can't have some control over whether they need more or not. Of course, that assumes that they really will seek out the free-choice source if they need it. If it's really true that they do, it seems like a good plan to let them control that rather than have it in the feed at such a high level that they can't avoid it if it was too much....