Do the new processors and cameras actually give you a better experience though? I used to upgrade regularly, but I'm still using my S10+ and I'm honestly not sure I'd've replaced my S8+ if it hadn't been stolen, I don't really notice a whole lot of difference. (If anything I miss the coloured notification light from the S7+).

I've found diminishing returns with upgrades recently. Since I got my iPhone XS I haven't seen anything pushing me to upgrade. I'll probably upgrade this year just to give my XS to my partner who is on a 6 and no longer receives updates.

Yeah, it's funny when people talk about workloads on their phone lol. I use it to text, make calls, slack for work, watch the occassional video and take some pictures. I'm not exactly batch processing 3d renderings on my phone and I suspect that 99% of the people out there aren't either. My 3 year old iphone is doing fine. as long as it gets security updates and isn't laggy it gets to live.

Yes. It's not that the old phone is unusable, but the new one will be noticeably faster and that's worth it to me. My most recent upgrade was going from an XR to an iPhone 12. If you compare the benchmarks, the 12 is ~30-50% faster for most workloads. And you can feel the difference when you switch between them.