The middle one is an iMac 5k, the exterior ones are 2x 24" 4k Displays. There’s no such thing as too many displays, haha!
But yes, productivity wise, I can’t work without at least a secondary screen. I keep either my Todo List / Calendar on the second one and browser on the third. Middle is for code and design.
I definitely recommend investing in a secondary display. Your working efficiency will change radically after doing so, and you’ll never wanna go back!
And I also forgot to mention. It has split view functionality. Vertical or horizontal. So you can keep your HTML on the left side for example, and the CSS and JS on the right. Making your workflow much smoother than switching between files constantly.