What the subject line should say is
Before All Else Set Your Speakers up Properly. Here is a point against the multiple monitor thing.
One should be mindful of the fact that the moment you introduce a second or third monitor speaker placement starts to go out the window to ensure one can see all their monitors. Look at the set-up in post #25 for example. Sure he has got three monitors but his speakers are way up high. Very poor. If you have to stand up to hear your speakers clearly you have failed in my opinion.
We are in the business of producing audio and that involves using our ears. More visual devices do not help, they only get in the way. There has already been a lot said (by experts) about turning off your monitor(s) or covering them up and just listening. It is quite interesting actually. Ever tried it?
A well designed program can easily work only on one monitor. My work flow is a fast as any person here with three monitors probably faster.
Even
one monitor can skew the sound in between your speakers. In mastering situations the monitor placement is often for the benefit of the sound not the visual.
I say get your speakers down into the right position, set them up properly, set them the right distance apart, position yourself the right distance from them and revel in the sound. That will improve your production many many times more than getting another monitor and it does not cost a thing! The more you listen and use your ears the less interested you actually become in monitors and you find yourself getting rid of them rather than accumulating them.
PS Remember the old days, there were no monitors and they manage very well. Very well in fact. The guys that need the monitors are the TV editors and maybe the Stock Market dudes!