I am asking out of curiosity and nothing else: what use cases do you have that motivate you to get a new phone every year? Do iPhones get notably better with every release? I'm guessing camera or storage would be big ones?
Well, with this last one they finally made the telephoto 48MP. Also, vapor chamber is nice. I don't know if the 18 will have enough for me to upgrade, and it might even have a reason for me not to upgrade (removing gestures from Camera Control). But so far it's been every year, because I've only been using iPhone for a couple years, and my first was a refurbished 15 Pro Max.
The 17 Pro (non-Max) only comes with up to 1TB of storage, but that's still more than my 15 of before.
I'm not parent but a counter perspective - the only three motivations I have are: phone dies camera vastly improves (imo it's been on a decline since the Nexus 6) phone is too slow to use
I'm on year 5 of my Samsung s21u that I can replace the Samsung ux slop with asop ports