I rarely switch phones for no reason. Just like someone stated below, I like to use a particular phone as long as it still functions well. If ever it develops a faulty part or catches a bug, I simply fix it. The only time I get to change a phone is when it crashes, goes missing or gets stolen. The two later happens more often with me, so it's likely you'd see me using a new phone every couple of months.
Come to think of it, there's this one time I used one particular phone for almost two years without any mishap. This was back in the late 2000s' when blackberry was dominating the market. It was my first blackberry device, Curve to be precise. You can say I had the blackberry fever, this is because I never could spend more than an hour without getting my fingers busy with the phone. This is probably why I didn't loose it. Unfortunate, I crashed and I had to change it because it wasn't fixable.