Every 4-5 years I replace. But basically I've been on-call for work for decades, and it's absolutely affect me psychologically about using it. It started with a pager, then two-way text pager, then a blackberry, then a mobile, etc. So long before smart phones were a thing, I was trained that the mobile device was a leech, and when I wasn't on call I would not carry it because people would try to reach me for help anyway because I was that guy who could fix it.
So I never got used to playing games, or full time social media, or any of that. Even now I have no social media on my phone, I think one game (co-written by a friend who's a "Consulting Mathematician" like Sherlock is a "Consulting Detective"), and texts and backup kindle are my biggest uses.
My current phone is the first time I've replaced my phone without it dying, got it earlier this year. But my $120-in-2014 unlocked phone was just getting too pokey even for me, and I wanted a better camera.
