Software-wise, I've been with Cakewalk since the mid 90's upgrading at least every 2 versions, but I've upgraded every version since Sonar 8.
But for PC hardware, I've tended to hang on to my system as long as is possible - up to 10 years if I can - although I might upgrade my processor after 5 years or so (from middle of the range to top of the range) once the prices plummet.
I'm currently maxed out processor-wise on my current motherboard, but it's not struggling in any way.
The last time I upgraded my PC was when X2 stopped supporting Windows XP, but even then I was still running 32 bit on Windows 7.
It was only when I wanted to use some 64 bit only plugins that I moved to Windows 10, and then as a result had to retire my 2 x Yamaha DS2416 PCI cards which I'd used in all my PC's since 1997.
In fact, it wasn't until I moved to Windows 10 that I started using VST's & VSTi's in anger. My 2 x DS2416's had EQ & dynamics on every channel, and 4 x effects; and all my synths were hardware.
Prior to X2 I was using an Athlon 4000 (2Ghz dual core) with 4GB memory running XP 32 bit. I used that since around Sonar 5.
Before that it was a Athlon 800Mhz machine (later upgraded the processor to 1.2GHz) with 750MB RAM. I'd had that since Sonar XL.
I think CWPA 7 through CWPA 9 I had running on an old Cirrus P166 (64 MB RAM), but still with the Yamaha DS2416.
And before that... 10 years of using an Amiga 500 with Music-X, using a Yamaha MT1X 4 track and later a MT8X 8 track.