Each set of trays is worn for 6-8 weeks before being replaced with the next set in the series. The frequency at which you will receive a new tray is largely dependent on your consistency wearing them 20-22 hours per day. The total number of trays needed for your treatment will vary based on the complexity of your case and the specific movements needed to achieve your desired results. Some people may only need a few sets of trays to achieve their desired results, while others may require 20 or more sets.