I explicitly do NOT upgrade very often. My Macs are on six to seven year replacement cycles. A couple of times I've had to buy at shorter intervals, but that is because my requirements changed.
Oh, and I'm a power user too. I hit some of the CAD stuff very hard - it's moderately often that I run some single-threaded things for two hours at a time, and it's also a moderately common occurrence that I pin 10+ cores on this M4 Max Studio, although those periods don't last more than a handful of minutes at a time. I am actually exploiting the 40-core GPU *and* the 16-core Neural Engine. Some of my photography and video stuff also hits the machine very hard.
And yet I'm not even remotely considering an M5 Max upgrade for 2026. An M6 upgrade in 2027 is both unlikely and probably economically infeasible - this machine put me back $5k. At best (worst, really) I might consider an M7 Max or Ultra in 2028. More likely this 2025 machine has to last me until 2030 or 2031.
I also have the additional complication that it's not just this desktop. I have a 2021 M1 Max MBP that will need replacing sometime around 2027-ish, and while it will probably be replaced with some kind of Air, it won't be one of the lower end model Airs. And my wife's 2022 MBA will also need an upgrade eventually - I'm hoping to avoid that until 2028 or 2029 since she is a much less demanding user than I am (she is a writer and novelist).
Considering that we're on 7-year upgrade cycles on our iPhones (11 and 12 Pro) and that she also uses an iPad Pro that will become Vintage in 2026 or 2027, even these very extended replacement cycles mean that we're shelling out on a big expenditure practically every year. Now that the kids have achieved escape velocity and are contributing members of society, I need to worry about two phones, two laptops, a desktop for me and an iPad Pro for her. With six major devices on 6-7 year cycles, it's almost affordable. It would be utterly unrealistic, to say nothing of financially stupid, to upgrade these *tools* even every OTHER year, let alone every year.