My base flock are 5-6 years and still lay every day or every other day in peak season. I kill any that don't lay that often and I check yearly for laying, so anyone who makes the cut stays here...I have 11 of the original flock of 20 bought that year as chicks. Husbandry methods and general flock management can help your flock have more longevity of lay and it helps if you start with great laying breeds at the beginning.