We would suggest you use your own intuition on deciding when you need new tones. Some clients have had the same set for a year and others get new tones once every several months and others every few weeks. Each new set of tones is like peeling off another layer of the onion (so to speak). The more you listen and the more you update them the more the will work with you to release old patterns that are holding you back in your life. If you are looking for a tool that can assist in your evolution than nothing gets as easy as this one.