Pretty much this.

It tends to depend on your branch, though, and in some fields, you really don't need anything other than your code, because you're not testing anything before it's compiled anyway. For something like frontend development, on the other hand, having some extra screen space is a blessing, be it more monitors or just one bigger monitor, especially if you have the tools to easily manipulate the screen space, like automatic window tiling.

To take the frontend example further, when you have something like i3/DWN/sway or any other tiling windows manager (that's on Linux), you can easily set up more "desktops" (workspaces), divided into tiles like the browser window (to preview the changes), your editor (to make the raw changes), and the developer tools of the browser you're currently testing things on. Not like it's impossible to achieve the same with any other tool that lets you create virtual desktops, but the less time and brainpower you use on switching tabs/desktops/workplaces, which you achieve by always being able to access everything you need at a glance, just kinda helps you enter the flow state - you just dissolve into the process completely because you stare at everything you need all the time.

The more you need to look at, the more you gain with these setups. The frontend example from above is a rather simple scenario, which is not too likely in this era, because you're pretty much guaranteed to be using at least one framework, most likely with a live preview feature with real time output of the compiling results and errors. There's no shortage of windows to open, all of which will be relevant and useful to your current task.

Either that or put some non-work related crap on the side to switch to whenever you get mad because you don't get the result you wanted to.