… if you know how to use virtual desktops and shortcuts. You can’t look at two screens at a time, anyways.
One use case I can understand is having a 2nd monitor for checking stock prices or checking for a certain event. Other than that, I don’t see how it contributes to “productivity” while working or coding for example.
P.S: Tiling WM users may understand this post more
I’ve always changed tabs, or at the very most, copy-pasted. I don’t use split-screen though, as I find it too overwhelming and cramped for me. I’ve never found a reason to have 2 monitors.