To those with 2+ monitors on your machine: What's your use case, and how much does it actually boost your productivity?
I'm mainly curious about software developers here, or anyone else whose computer is somewhat central to their life, be it professional or hobbyist.
I only have two monitors—one directly in front of me, and another to the right of it, angled toward me. For web development, I keep my editor on the main screen, and anything auxiliary (be that a dev build, a video, StackOverflow, etc.) on the side screen.
I wouldn't mind a third monitor, and if I had one, I'd definitely use it for log/output, since currently it's a floating window that I shuffle around however necessary. It could be smaller than the other two, and I might even turn it vertical so I could split the screen between output and a terminal, configuring a AutoHotKey script to focus the terminal.
I'm more productive than anyone else on my team, and would argue more productive than the majority of people in my whole department. I use a single 28" monitor.
I have lived with multi-monitor, but I have to say I don't generally feel the need and haven't for a few years. Desktop workspaces and a tiling WM help a lot.
The one exception is if I'm doing web dev, where I need the browser, the browser dev tools, and my IDE, and having two monitors can be nice. But that's occasional for me, and I make do with opening the laptop and using it for the browser, and then having the dev tools + IDE sharing my 27" 4k everyday monitor.
Most of the time I can only read one thing at once anyway and I want it in front of me. I have hotkeys to switch workspaces instantly, which is often less disruptive than swiveling my eyes/head between two monitors. Any screens beside my 27" monitor are too much of a head swivel for more than transient use anyway.
...there is no point other than "I am better than my peers" being made here. I.e. all of your coworkers could have no monitors. Also sure your better than them, but are you better than yourself with multiple monitors?