I have never, in 30 years, working across big companies and small, had a computer hardware upgrade. It’s _always_ just a new box.
But even I haven’t done that in several years now, once IT moved to providing 16GB memory and SSD’s as a baseline, there’s really nothing left in a box to upgrade. I’m quite happy enough to not have to care.
This is especially true if the business is writing down the replaced hardware as depreciated capital, compared to say simply adding a stick of RAM.
Aside from that, almost always a new PC - almost! When times haven't been so good, I've had spot upgrades.
All of the above is just a question of running the numbers and minimising for cost, I'm sure.