If I remember my biology correctly, every female is born with a predetermined number of ova. This being the case, the longer it takes for her eggs to be shed, the longer she will have them. Therefore if you aren't using lights and your hen lays 1 or 2 eggs per week as opposed to 4 or 5 under lighting, then she will lay longer in terms of the length of time you'll get eggs from her but not in terms of the number of eggs--either way she is eventually going to go dry. The biggest argument for not using light is that the hens need a period of rest and, without it, will develop problems with their egg laying apparatus. I use what I consider a reasonable period of light, always have, and never had a particular problem. Since my hens are not pets but are here to produce eggs, I want them now rather than later, Besides, chickens have a way of dying of various, non-egg laying, causes and I'd just as soon get every egg from each hen that I can before she passes on.
