When working on console games I've always found it useful to have one screen (in this case, a TV) dedicated to your program, and 2 left for use with your PC. When working on PC stuff I've also used a similar setup with a second PC as well (with its own keyboard and mouse, no Synergy/KVM/etc.). So I was expecting having 3 plugged into a single PC to be just as useful! But I had the same experience as you. I used it for about two weeks before I had to admit that the extra monitor was just one too many.
I do wonder if it's just the aspect ratio of the desktop area though. I feel like if I had two landscape monitors on top of one another, and one portrait to the side, that would be more manageable.
(The horizontal arrangement of monitors is more common, but actually I think the vertical one is much better. I currently have my laptop sat under my main monitor, and it works very well. With a horizontal arrangement I've always found myself ending up with a preferred monitor straight ahead and spare less-used one(s) to this side. After all, who wants to keep having to turn their neck? But with them stacked on top of one another, all you need do is glance up and down, and they're all equally useful.)
I do wonder if it's just the aspect ratio of the desktop area though. I feel like if I had two landscape monitors on top of one another, and one portrait to the side, that would be more manageable.
(The horizontal arrangement of monitors is more common, but actually I think the vertical one is much better. I currently have my laptop sat under my main monitor, and it works very well. With a horizontal arrangement I've always found myself ending up with a preferred monitor straight ahead and spare less-used one(s) to this side. After all, who wants to keep having to turn their neck? But with them stacked on top of one another, all you need do is glance up and down, and they're all equally useful.)