So I told myself for a while as I used a tiling wm with a monitor, and then switched to two, and now using three.
There's something in the human brain (or at least, this human's brain) that makes it easier to keep a mental context on something when you can physically separate it rather than virtually separate it. My browser (regular spanish/english text, light work) is on my left, my code (IDE/text editor) lives in the middle and music/test suites/compilation pipelines lives to my right.
When I use my laptop, despite having as much resolution as 4 monitors and using almost the same exact tiling configuration, I find it much harder to focus as comfortably as I do on the desktop.
Mind you, I admit to very rarely making full use of the third monitor, but the second one? Absolutely, wether it's backend, frontend or whatever.
>On a single monitor, this means endless clicking, scrolling back and forth on the page you are trying to debug, next think you know, your fingers and wrists are sore and you haven't gotten too far in your work and your coworkers tell you that you have RSI.
Trust me, neck problems due to constantly looking at 2 monitors is as bad.