I used to change every 2-3 years, usually when one of the new ranges came out and caught my eye. Last change like this was to MP64s which never really got broken in before I had an accident that changed everything. My Rehab irons were the 2014 JPX EZs and they were great, I've only just bought a used set of 900 Hot Metals as my game is slowly coming together and I don't quite need all the help the JPX EZs gave me.