Rarely. The dual Xeon X5690 5,1 in my signature was the quad-core 3.2ghz Xeon 8GB RAM 1TB HDD machine I purchased brand new from Apple. It has upgraded wifi and bluetooth so it has all modern convenience features. Same done for the other 5,1 (which I got second hand for its dual-CPU tray). They are both quite snappy machines.
The 6,1 the only thing done was upgrade from 2.4ghz 12 core to 2.7ghz 12 core. It is still quite quick and does what I need it to do, with a benefit that it is relatively portable.
The 7,1 is going to get some RAM upgrades and my eye is on a W3275M Xeon (28 core 2.5ghz). If I see W6800X Duos available at the right price I'll grab those first. Currently it is doing the job with no issues and is the most reliable machine I've used.
Aside from that they all just run fine. 6,1 and 5,1 machines are all on Monterey.
Next upgrade is likely Lenovo Thinkstation PX to replace 7,1 when it is no longer fit for purpose.
The M2 Macbook Air is relatively new, it's used only when I'm abroad or need to do work where it would not be practical to take the 6,1. I'm not sure how the MacBook Air will go in the later years and who knows if Apple might decide to drop support for it suddenly with little warning. I'm happy with that laptop so far. It's not the fastest but the battery life is good and the screen is okay. If I were buying it again I wouldn't go for the midnight colour, that shows every fingerprint and scratch.