Cooking chicken soup for a longer duration can enhance its flavor and tenderness by allowing the ingredients to fully meld and the flavors to intensify. Note, extra cooking should be done over a very low simmer. However, other ingredients with specific cooking times need to be considered such as pasta and vegetables, like zucchini, which can become mushy when overcooked. There is a point where overcooking can lead to the chicken becoming dry and the soup losing its desired texture, so finding the right balance and cooking time is important.