All flock type feed is better for mixed gender and mixed age flocks. All flock feed is any poultry feed that's not a layer feed. All have about 1% calcium but layer has 3-5%. Basically if you run a mixed gender or multi age flock using a layer feed is not your best choice. By simply keeping a dish out with oyster shell in it the birds that need the extra calcium will eat it. Free choice and they figure it out themselves. That's as easy as it gets and you end up feeding better quality feed (higher protein) for same price. Oyster shell from the bulk bin is around 30 cents a pound and my 10 hens go through maybe 15 ish pounds a year.
It's not that grown cockerels/cock birds can't eat the added calcium. For adult non laying birds the health effects take years to catch up to them. So unless you really want that cock bird to live more than 4-5 years then don't feed them layer feed. Where layer feed really hurts is young birds. It horrible for young birds and if pullets are on a high calcium regiment long before laying it can cause issues like egg bound when starting to lay.