I use two 27" monitors at work and would definitely feel a productivity hit if I were to go back to smaller or fewer monitors.
I dedicate one entire monitor just to a full-screen terminal with tmux running inside. It's trivial this way for me to edit and view and compare multiple files at once. I typically dedicate half of the second monitor to a browser, for testing, and the other half to administrative applications, like email, Jabber, and IRC.
The result is that the cost of context-switching is drastically reduced. I'm able to maintain focus for much longer stretches of time because I don't really have to ever completely switch contexts.
A tiling window manager would blow your mind. Anyone whose productivity is improved by using tmux should really try out something like i3 or xmonad or awesomewm.
For me, just turning my attention (and my head) to a second monitor is too much. I greatly prefer multiple workspaces/virtual desktops to multiple screens. I'm fine with completely switching contexts when the cost of context switching is 0.
I guess I can sort of understand this viewpoint, but I barely have to turn my head at all to go from looking at code to the browser. I can move my eyes between code and the browser (for instance) faster than I can switch between virtual desktops.
I dedicate one entire monitor just to a full-screen terminal with tmux running inside. It's trivial this way for me to edit and view and compare multiple files at once. I typically dedicate half of the second monitor to a browser, for testing, and the other half to administrative applications, like email, Jabber, and IRC.
The result is that the cost of context-switching is drastically reduced. I'm able to maintain focus for much longer stretches of time because I don't really have to ever completely switch contexts.