Very. A rooster requires much less feed than a hen, and is naturally inclined to spend a lot of time helping her find the best foods to supply her eggs and in future the chicks that hatch from those eggs.
The best roosters do some kind of measuring, like a hen with chicks will, of food. By sight alone they judge whether or not it's enough for their priority; which is for hens and roosters alike, chicks, and for a rooster with hens but no chicks, the hens are the priority. If he thinks they need feeding up, and doesn't think there's enough for him too, he will stand back and not partake. This is a best case scenario of good instinct in action. Many chickens have had this bred out of them. I highly value it in my flock because contrary to some opinions, in my experience anyway, more instinct equals calmer and happier non violent birds. Many people associate instinct with violent and terrified birds, but that's one instinct they're thinking of as representing all the natural ancestral instincts. Tame but otherwise instinctive birds are great in my opinion.
In desperate circumstances roosters have been known to starve to make sure the hens are fed, and likewise the hens with the chicks will starve if necessary to ensure the chicks are fed. Chickens are, in the wild as well as some in domesticity, extremely social and family oriented birds, which is another reason nobody should tolerate a hen or rooster who kills chicks as that is extremely aberrant.