Assuming you take good care of your equipment and don't need to upgrade often, I'm guessing this could take many years, probably a decade.
My last decent Windows machine was a Lenovo T530. That thing was a workstation and didn't pretend to be anything else. Modular, easy to replace components, that thing got out of my way and just worked. That was over a decade ago.
After that I had nothing but irritating issues. Everything from poor wifi (looking at you Killer), poor battery life (2 hours max), ventilation issues and overheating, etc. Example: My Dell XPS with InfinityEdge screen looked amazing. What was less amazing was the constant BSODs on a brand new machine within a few months of light usage.
I switched to a MBP Max M1 and haven't looked back.