Depends heavily on the pace of technology improvements and if there is anything worthwhile to upgrade to.
I remember there was a lull for quite a long while with almost nothing significant coming out in terms of higher refresh rate, resolution, colour depth etc... for several years - 1080p 60 Hz blah blah blah all the same. I was on a Dell WFP3008 at the time, I had that for many years.
Since that lull in improvements ended I've had three I think, most recent is an 38WN95C-W (38", 3840x1600, HDR600, 144 Hz refresh) which I upgraded to from an Acer (I forget which model) that was 34", 3440x1440, 60 Hz, no HDR.
I won't be going for anything bigger than this as a primary monitor (nothing bigger would fit on my desk), so I guess I won't be upgrading again for a fair while, maybe once 8k becomes viable. There are some 8k monitors available already, but no graphics cards capable of gaming on them at sensible framerate/quality settings.