At work (I remember the place well!) I have a pair of 1920x1024's. What size? Not sure. I rotated them 90 degrees, so there are two vertical panes of 1024x1920, side by side, making a 2048x1920 area.

Approximately square is the most productive size. When we're working with text, be it code or prose, the height of it is unlimited, but the width isn't. So it ends up in multiple columns.

Books are mostly oblong (taller than they are wide), but that's only if we think of them in their closed state. An typical open book is typically a bit wider than it is tall (but not greatly so), and you have two columns of text (the two pages).

That open book geometry is an awful lot like my rotated monitor setup, isn't it.

Until I rotated the monitors into this configuration, I was consistently just using one and ignoring the other. Moreover, ironically, using virtual desktops! I keep virtual desktops as large as 4x4. I would rather pane among virtual desktops with hot keys than turn my head between two excessively wide monitors placed side by side.

People made remarks about my disuse of the second monitor, which prompted me to come up with a good way of using it.