We all have our own goals and reasons for keeping chickens. Some for eggs, meat, show, pets, bug patrol, breeding, and who knows what else or what combinations of these. You will have to find your own answer to this question, it doesn't matter to you what I do. My goals are different from yours.
It can vary by individual hen but a normal sequence as far as egg laying is that the pullet will sometimes lay throughout the first winter and skip the molt, some don't. She'll lay pretty well until her first adult molt. That may be her first fall/winter or it may be her second. She stops laying during an adult molt and uses the nutrition that was going to egg production to grow her new feathers. Then she starts up laying again after the molt is over. After that first molt, she still lays really well in number plus the size and quality are even better than her first year. Some lay more than others but before and after the first adult molt are usually her best production cycles.
After her second adult molt her egg size improves a bit but the number of eggs she lays tends to drop off. Each individual hen is an individual. Some may drop off a lot, some not at all. In a commercial flock with thousands of hens the average drop in number of eggs is around 15% but you don't have thousands of hens. Pure luck on which category your individual hens fall in will determine what happens to your flock production. The production drops after each subsequent adult molt so soon you aren't getting much production. After several years the quality of the eggs might deteriorate, thin shells or runny whites, for example. How much deterioration, if any, will depend on the individual hen.
For my goals, I am on a two year rotation. I normally keep four pullets each year as replacements. I'll keep the four pullets from the previous year through their first molt and the next year's laying cycle. At the end of the current laying cycle I'll eat the four hens that have already been through one molt when they start their second adult molt. So when the pullets come into lay in late summer or fall I'll have 12 laying but I only carry eight through the winter.
You will have to determine your own goals and decide what works best for you.