When optimizing contacts, Optimize has several rules to manage contact fatigue such as Max # Duplicate Offers, Max # Packages, Min/Max # Offers, and so on. All of these rules include the over the time period or within the time period section.

If you always set the time period to 0 in all the rules, it indicates that this Optimize session does not use time periods for any of the rules. In such a case, you can control how Optimize queries the contact history tables during the Optimize session run using the UseFutureContacts configuration property.

If you set UseFutureContacts to false, Optimize optimizes joins with the contact history tables if your rules include time periods. If your rules do not include any time periods, Optimize does not query the contact history tables at all, which can improve performance.

If you set UseFutureContacts to true, Optimize always queries the contact history tables. While this impacts performance, it also ensures that placeholders for contacts that will be sent in the future are considered when managing contact fatigue.