Most years the camera improves enough to be worth it for me and I have a few different people my hand-me-down phones go to so it averages to 1 new phone every 4 years for the group.

I seem to be hard on my devices. They get nicked, scratched screens, battery worn. I am wealthy enough that this expense is not particularly impactful to my financial goals. So, I upgrade yearly. I am seriously considering not going that way this year.