Humans evolve. Computer systems aren't exactly "spatial", and virtually all attempts to model them as such have failed. We ought to strive for future vision.

1) False. Software screen switching is easily instantaneous. If you literally have two front buffers which, you must for a dual screen setup... there’s no reason you couldn’t flip between them at the refresh rate of your monitor (which is ridiculous but doable). Workspace switchers that run on shitty old X can be and many are effectively instantaneous. Not sure about Windows, but I assume something exists.

There’s more to life than Mac OS X.

3) you can still have a spatial layout of workspaces even with one viewport.

How come in people have been shown to be more productive with dual screens?

Well I didn’t say multiple screens didn't serve a purpose, did I?

Having said that, is there any good evidence of a fair comparison of dual screen vs a fast switching single screen. Most Mac and Windows setups make switching so tedious and slow it’s pretty obvious that dual would be more productive.

I would not be surprised that a truly friction minimized single screen setup (total switching latency from input to display <100ms... which is technically easily achievable (and done in many special purpose devices... just not in PC software).. and ergonomic switching key would approach dual screen in productivity. I mean, this is the typical setup I and many others use on a Linux laptop for dev work. By the time someone gets MC on OS X up, I can literally switch “screens” 3 or 4 times.

I enjoy a multimonitor (4) setup, but I’m not about to trade off battery life and space for it on the road.

Frankly it’s just easier and cheaper to buy a second monitor with state of the art, for most people. I get that. I use OSX and Windows too.

Also, I would expect more than 2 monitors to increase the gap.