Duplicate Detection should only be run On Create or Update of a field involved in Duplicate Detection rules. Currently, if a record that meets the duplicate detection criteria is opened and saved the duplicate detection message will appear. That means if a User is aware of the duplicate detection and has made a conscious decision to override the warning and continue with record creation, they will get an annoying duplicate warning every single time they open the record and save it. Even if the update they made to the record had nothing to do with the duplicate detection. So if they make a daily update to the record they will consistently get an annoying message that slows down efficiency.