There is no such thing as too much desktop, as far as I’m concerned. In my experience, all software developers can increase their productivity with a second (and even a third) monitor. Data analysts and scientists can also increase their productivity with a second monitor.
At work, I leave my 1920 x 1200 laptop screen open to serve as a second monitor, and for work at home I bought a second 1680 x 1050 monitor a few years ago. What windows do I place on my main monitor? My IDE’s window and the web page I’m currently working on. What windows do I place on my secondary monitor? My email program, my journal document where I track what I’m working on, and my primary Cygwin console window from which I launch additional mintty windows. I often also need to make space for a spreadsheet window and a bioinformatics tool window. If I had a third monitor, I know where those extra windows would end up!