'Needed' is too strong a term. I function OK on a single screen laptop... But I've got a second screen in my laptop bag for when I'm going to be sedentary for

'Needed' is too strong a term. I function OK on a single screen laptop... But I've got a second screen in my laptop bag for when I'm going to be sedentary for several hours. I work in 6x10 font on my emacs at my main workstations, so I'm moderately small text. I stopped using 5x7 some years ago. But somewhere in there, you start using mental effort to resolve the smaller features. The big reason I prefer more real estate is that it's desperately more mentally efficient to e.g. trace through multiple levels of abstraction with your eyes, than with eyes plus fingers plus reorient on the new desktop configuration. Just having "the usual" fullscreen editor setup on one screen, and "the usual" browser or mail setup on the other is a huge improvement.