My last phone broke after about 1.5 years of me using it (and it was already a refurbished device), and my current relatively new-to-me phone only has 2 years of security updates left (also refurbished). I’m probably going to use it for longer than that if it doesn’t break, but that would definitely be a good time to get a new phone if money was no object and I didn’t give a shit about the environment.