I just upgraded my laptop from a 4 years old mbp to a brand new one, got a 27" second screen display, and i can tell you my productivity has been skyrocketing.
Performance gains are obvious, but the psychological aspect is also a factor. After working for a year on the same project, new hardware can bring some new joy, and a new boost to your project.
Do you have more pyschology and well being tips? Mine would be: live healthy (diet, social life, exercise, sleep) and do what you most feel like doing, even something premature optimization (within limits).
4 years is reasonable. But the OP just says 'upgrade often' which might mean anything and as such reminds me too much of iDiots [1], which is imo not what your upgrade strategy should be like (i.e. upgrading for the sake of upgrading).
Over the years I tried different upgrade schemes, and it seems 2 or 3 years works best for us. Over the course of that timespan there is an overall performance gain large enough to notice and worth money. If you go with less, say 1 year, the gain is much smaller, and you essentially pay for something that's the same but just looks newer. Also depending on the country you live in, there's a certain amount of time you can use hardware as an actual cost on your tax form. As such keeping it much longer than that time means loss, keeping it much shorter as well.
The psychological aspect (which we all know since childhood already and basically is set in our genese: new = interesting) does do something, of course, but has in my experience no long-term effect whatsoever apart from it costing money. Especially with short upgrade cycles the 'wow, new' effect gets less and the money effect more.
I replace my main computer (MacBook Pro) every 1-2 years with a maxed out top of the line model. I keep the one I had before around as a backup in case my laptop breaks or gets stolen.
Yes, it doesn't make too much sense tax-wise. However, it would cost me much more in productivity to wait 2-3 years longer to replace it. This thing needs to run bunches of stuff for development, like various DB servers, multiple VMs (yay 4 different versions of Internet Explorer) and should be as light as possible so I can take it everywhere easily (usually servers go down when you're mid-vacation).
So it might save a few hundred dollars by taking advantage of tax laws, or I might earn thousands more because I can develop faster and things are just more enjoyable. I know what to pick.
This is true - must admit I didn't consider it/forgot it as I'm not a big fan of saving on these from the start: when we buy new workstations, we immediately get them with plenty of ram (which is rather cheap anyway) and screenspace (which is productivity-wise way more important for me than raw computing power)
