Table linens should ideally be changed after each event. This ensures that each guest experiences a clean and well-presented environment. However, in the case of multi-day events or conferences, if the linens are not visibly dirty or stained, they can be used for a couple of days. It's crucial to remember that the cleanliness and presentation of table linens contribute significantly to the overall impression of an event. Therefore, regular changing and cleaning of table linens is an integral part of event planning and management.