[bryanrasmussen]

most people I see do this do it on multiple screens not multiple windows on one screen (or multiple tablet sized windows on one large screen, and most do it without making any screen as extremely narrow as the parent did.

However I suppose also that most is not all, and there must be some outliers who do it on a single laptop screen either from necessity or preference. I might find myself doing extremely narrow windows out of necessity but never preference, and then the extremely narrow windows would almost always be on something I was working on - as it is indeed in your case - and not to interact with someone else's site.