Like clockwork every two years since 2002. This year MAY be different now that I am in the Apple world and my phone still looks new. I May go three years and then pick up a iPhone 12 next fall when the iPhone 14 comes out.
Its going to be weird feeling 3 years on the same phone so I'll see if I make it!. Thing is my diamond condition iPhone XR is worth $207 on the Apple store right now, site unseen. Im sure I could get $300 for it on ebay. Not a mark on it. SO in another year, not sure if I will be saving money by waiting, yet, love this phone and dont feel compelled, YET! I still have 3 months untill two years old in December ! *L*
But then again, the new Apple Watch 7 will be out, that maybe way more compelling enough to hold off no the phone 1 year.