Ditto.
I have two phones because one is provided by my employer and is locked-down according to corporate policy.
Although I could use my personal phone for work, the IT department would insist on installing their security software including (for example) the ability for them to remote-wipe it without my knowledge.
So even though I could install both phone numbers on my personal iPhone, I’m never going to do it.
When I was buying a phone, I’d get every other version (so I’d keep a phone for about 2 years. However, now that I’m on the Apple Upgrade Program, I get a new phone every year. My monthly payments are constant; they just never end :).
I’ve had
Looks like it has settled into every five years.
When it stops working! I’ve stuck to the SE as I want it small enough to be comfortable in a front pocket. Not sure what I’ll do when this one fails.
I upgrade when Apple releases a phone that’s a reasonable size. I went from the 5s to my current 12 mini. That was a 7 year gap. 
that Apple releases another ‘small’ phone by 2027.
Every 2-3 years.
History (all bought 1-3 months after announcement)
Going forward, I’ll probably upgrade every two years (starting with 17) because of my carrier (T-Mobile) subsidy.
A good 10x or more telephoto together with improved OIS which allowed one to get sharp photos handheld would make me consider switching from my 13 Pro Max. I still have excellent battery life on the phone despite the battery health being 87%. Everything else (AI, thinness, foldable, size of camera bump, additional buttons, more deluxe material, etc) is of no importance to me.
My former phone was a 7+, which is still very nice. A newer phone might be 2x as fast - that means that it will take 0.5 sec instead of 1 second to do something. Actually, I prefer the LCD screens except in bright light or when watching a movie with lots of dark scenes, something I rarely do on my phone. I hate the notch, rounded corners, and color changes when I tilt the phone with a white background - these are “issues” with recent OLED phones.
iPhone > 3gs > 4s > 6 Plus > Xs Pro Max > 13 Pro Max > 16 Pro Max
I started at every 2 years, but now buy every 3 years. Starting with the 6 Plus, the old phone became my wife’s phone when I got a new one. She’s fine with an older device.
When my wife gets a new phone, hers gets repurposed into something else; home controller, doggie camera, test unit. I usually get 10 years out of each one.
Much like Macs, I used to upgrade my iPhone regularly. But the category is mature now, and new phones cost much more than they used to. I plan to keep my 13 mini until it’s no longer supported by new iOS releases.
(It’s not that I care about what is in each new iOS version – iOS is pretty mature now too – but I don’t feel comfortable using a device that’s no longer getting regular security updates.)
4, 5S, 7, 13 Pro.
Slowing our cadence. And we may be over paying the Pro premium as long as the regular model has enough storage. Assuming I can get a battery replacement at some point I have no particular urge to upgrade.
Dave
I started with the original iPhone and got a new phone every 2 years. I retired in 2021 and bought a 14pro when released in 2022 (which I’m still using). Now I’m paying for my own phones I’ll only update when there’s something compelling or a major failure (battery etc). Maybe next year…
My watch is a 6 and I’ll update when the battery fails (it’s already had one replacement). I have an iPad which is probably 5 years old but as I barely use it I have no plan to update.
My main Mac is an M1 Max MBP and it’s going strong - amazingly good machine. I also have an M2 MacMini. No plans to update either of them.
And I meant to say my 6 is still working… don’t know about when updates fell off the possibilities, but for basic stuff, its absolutely fine bar a short battery life. It’ll be my travel iPhone next time I hit Boston.
Given how much I use and depend on my iPhone, when keeping one for multiple years I got tired of assiduously managing my battery charging schedule to maintain and preserve the phone’s battery life.
So I switched to Apple’s iPhone Upgrade Program (IUP) wherein for one makes monthly, zero-interest payments on a 24-month schedule for an iPhone, with the ability to either pay off the phone in 24 months or trade it in after 12 months for a new model. I’ve traded in my iPhones every 12 months under this program for a few years now and it’s lovely.
Aside from regularly gaining the latest and greate in phone, camera and processor tech (useful since I use the camera when traveling a lot), it’s incredibly freeing to top-up my battery at will, and even act in otherwide-unadviseable ways like keeping my phone plugged in at my desk, knowing that doing so might affect battery charging ability longterm… but it doesn’t impact life much over 12 months so it’s not a problem for me!
Apple’s battery replacement service is not very expensive, especially compared with the cost of a new phone.
It looks like they will no longer work on an iPhone 6, but a 6s replacement battery costs $70. For my 13 mini, it costs $90. Other models have other prices.
Yes, buying an aftermarket battery yourself will cost less than half of what Apple charges, but I consider the difference to be well worth it, since Apple will do the work and the result will be warrantied.
Having done a few iPhone battery replacements myself over the years, I fully agree.
I wouldn’t say that the procedure is very difficult, but it is moderately complex. The risk of damaging the screen, especially for newer phones, is high enough that if an official Apple repair is available, whether through Apple or an approved third party, it’s almost always worth going that route rather than attempting the replacement yourself.
For example, a replacement battery kit for my iPhone 13 mini is around ~$40, while Apple (or an Apple-authorized BestBuy) will do the full replacement for ~$90. Factoring in the labor cost and the risk, the Apple way is the better way. I’d only do my own battery replacement for a phone that is essentially disposable.
My iPhone 13 Pro and my wife’s 13 Mini are both still going strong on their original batteries. We’ll probably keep them for as long as they keep working, or Apple has a very compelling replacement. The problem for my wife is that she has small hands, and thus would prefer that any replacement have a similar form factor as her current 13 Mini.
With the IUP it’s very freeing to never have to worry about one’s battery, including paying to replace it. And that’s on top of always having the most powerful processor and best camera tech and always be under warranty (including loss).
I’m going to keep my IP13 mini going as long as I can and, when its battery dies I’ll see if anyone can change it for me. My phone fits my shirt pocket, that’s where it lives. If Apple make another Mini however… though I don’t see it happening… it might be a long wait until I can afford to buy a used one.
About every 3 years.
With AT&T, the installment plans usually run 3 years. At that point the phone is paid off and I can get the new model on a new installment plan. The key factor is that I almost always get the phone for “free” with AT&T promos. The installment payment is accompanied by a matching credit.
So basically I can always have a Pro for “free” by remaining on their Unlimited plan.
I’d love a new phone every year but frankly the annual upgrades are not usually that impressive. But after 3 years, the upgrade is palpable.