I tend to replace my phone every 3 or so year, but not always with a new model. Usually yes, but I just got myself an iPhone 5 because it was so cheap (second hand), so I'm going to use that until the SE drops in price to $300 or so region, and then go for that. I have no interest for physically large phones.
Once every year and a half to two years. I try not to, but after that amount of time, the battery life on the phone is very poor and I also need a change.
Either when my old one breaks or becomes too outdated. Whichever comes first. I haven't actually had a phone for very long, but so far I've been through two different models in the past 2-3 years.
As in phone phone, I haven't replaced mine yet. Smartphone, on the other hand? Never. My only ipod touch broke once and I didn't feel like spending a lot to replace it.
Alas, now, I'm beginning to regret that with Pokémon Go out and whatnot.
Not all the time because I can literally use the same phone for years, but if it breaks, then I'll go ahead and buy a new one. What phone does everyone here use right now?
I had an 530 for a year before I get my next two 640. And so I keep it till it had it days or when I have the money to get an new phone. I used the 530 for some time till that day when I heard about the 640 and I thought to myself damn that's an good buy (sale) that I get headsets also for free and I needed an upgrade since the 530 was damn small