I guess it depends the type of work you do.

To me, since I always need to have two apps side by side, a 34" screen have done wonders.

I have my main app as a regular 16/9 window, and the secondary on the side.

By putting the screen at the right distance and height, I don't have to move my head and my eyes just move a little to go through everything on the screen.

And my main window still give me more information than if I had full-screened it on my MBP 14" screen (typically, I can see my whole Jira dashboard on the 34" screen while I have to scroll on the 14").

On the other hand, having two screens (laptop + external) is terrible. Not the same resolution, having to turn the head...

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One thing that is bothering me reading the article: I find the whole clutter on OP's desktop quite distracting!

The cables coming out of the laptop, the things on the wall behind the laptop... That's something that would definitely kill my focus!

At the office and at home, I've put a blank wall/separator in front of me so the only thing in my vision is the screen.