Like a poster above said, my wife and I purchase the newest phone every 3 years at this point (since we are on no contract, etc). We bought the iPhone 12 Pro about a year ago and plan to have the current phone for another 2 years. Every 3rd year, we just pay cash (never finance) and buy two new phones (one for each of us). Based on this cycle, we won't be buying new ones until the Fall 2023 phone release.

I'm not any expert, but I don't see any drastic improvements with this mid-cycle upgrade.