It just depends on the person. Apple marketing is strong, and many people love using their phone to the point that new features really do matter.In my opinion, any series of 12 phone are good to go for one more year without an upgrade.
I use my phone when I’m out or lying in bed, but not too extensively, so new features sound interesting, but I don’t upgrade every year or even every other year. It’s just not a priority.
The iPad, on the other hand, is a device I really use nowadays, and any new feature gets my attention and tempts me to upgrade. That device is my weakness, not the iPhone.