What is your reason for "five years"? And yes, Android ROM folks kinda shock me with how often they fiddle with their phones, and I also don't have time for that kind of business.
I suspect there'd be bursts of burning multiple in a single day, for what it's worth. People flashing a phone, realizing something isn't working after they set up their registration again, and having to flash again.
Five years because there was a link recently on HN that indicated that was the average length of time that the top-end Android phones get updates. It's the only metric I have seen regarding the useful life of an Android device.
I suspect there'd be bursts of burning multiple in a single day, for what it's worth. People flashing a phone, realizing something isn't working after they set up their registration again, and having to flash again.