This year I have used a lot of older birds that I would expect not to produce much if anything. They are such good stock birds I am giving them a try. To my surprise a few of them are doing what they should be doing, a great result but early days yet.
With my very best hens I try to pair them to only cock birds that are already filling eggs. I am not prepared to waste these good hens on dud cock birds. Using this techniques gives you a much better chance of getting something out of your better hens.