Pullets, the first years layers do lay very well in that first year. But I do not agree that things go downhill from then on!! My battery hens for example, some are 3-4 years old, and all are still laying at full capacity - they are free range. I have found that the pure bred do not lay as good as the hybrid hens at all. I had some marans, and the eggs were lovely being dark brown, but they definitely did not lay anywhere near as many eggs per year.
As I said my hens are laying very well, as are another lady who got some ex batteries from us. Yet two other people nearby have moaned and groaned their ex batts have not been good, and are only just starting to lay again after the winter. I suppose its like anything, there are good and bad.