On my 11 inch I use a single pane. On the 15" it works well when the laptop is on my lap, but less so when it's on the desk but, then, it has two larger monitors, one horizontal and one vertical, so I can still use the two-pane arrangement (typical use is program and test files side by side).
I cut my teeth on the Apple II+, with 40 columns. I agree that 40 columns would be silly, but keeping the text column narrow so that eyes don't need to move too much helps a lot. It's a readability trick used in print since ever. From my position, the horizontal screen spans about 60 degrees, which feels excessive. By the time my eyes marched from left margin to right margin, I already forgot what I was looking for.
I cut my teeth on the Apple II+, with 40 columns. I agree that 40 columns would be silly, but keeping the text column narrow so that eyes don't need to move too much helps a lot. It's a readability trick used in print since ever. From my position, the horizontal screen spans about 60 degrees, which feels excessive. By the time my eyes marched from left margin to right margin, I already forgot what I was looking for.