i give them layer! it’s just confusing because a lot of people say they still need the extra calcium and such
Setting out oyster shell, in addition to the use of layer feed, is a bit of extra "insurance", as the calcium needs of chicks will differ between layers and breeds. Think of it this way - a large breed chicken that only lays a medium egg 3 times a week probably eats a lot of food (and gets a lot of calcium from that food), but doesn't need a lot of it for egg production. On the other hand, a smaller "breed" that pops out a large or extra large egg most days (like the golden comet hybrid) need a lot of calcium each day - and though they will eat a lot of food, relative to their body weight, they may want a bit more to maintain peak production and their own bone density. Thus oyster shell = insurance.
and of course high calcium amounts can be harmful, long term, to non-layers, like your cockerels. and the more they eat, the more that excess calcium can try to build up, so larger, faster growing breed (like any of the "meaties") tend to be more susceptible to it. Its part of why many of us use All Flock plus oyster shell, free choice, for our mixed flocks.
I can't tell you what's best for your situation, that's something you have to decide for yourself, in view of your end goals, your time commitment, your local resources, space, and budget - but you are asking questions and educating yourself to make the best decision you can. That's never a bad thing.
Happy holidays, and fortune favor your chicken endeavors.