I have a 5 year old Welsummer that laid 4-5 eggs a week up until this spring. All my hens take the winter off. She seems to lay for a few weeks, then take a couple weeks off, then start back up again. My other hens are 3 and 4 and they still lay pretty much every day. I do supplement daily with a mix of quinoa, oatmeal, cornmeal, garbanzo flour, black sunflower seeds and ground eggshell mixed with a little water. Just 2 cups for 7 hens but it seems to make a big difference in how steady the egg production is. It is their afternoon snack and they come to the back door for it every day.
We are not in the chicken business primarily for eggs- these ladies are pets but I regularly get 2 1/2 dozen eggs a week which is plenty for both my family and my preschool.