How much time do developers spend on side by side buffers?

I get the difficult to scan point (although I find it subjective) but the side-by-side argument is optimizing for a comparatively small use case.

    > How much time do developers spend on side by side buffers?

In my case: all the time. On my desktop (which has a large display) I often tend to have 3-4 vertical buffers open. Being able to fit all my code in those buffers is a godsend.

I know this is a bit of a rare condition, but I have very sensitive eyes, so I need to work on a single small laptop screen with decently large font size, otherwise I get eyestrain and I'm out for a week. So when I have two emacs windows open even 80 characters wraps around. I put up with it, but when a codebase has something like 70 or less characters per line I find it much easier to develop in.

It's my default. On the left buffer I've got the implementation, on the right buffer I've got the spec/test.

It's my default mode of working. Even in a statically-typed language (I mostly write Haskell these days), I often have one buffer for the things I'm working on, and 1..N buffers of references or parallel changes.