The main period of my life when I used a lot of footnotes was, unsurprisingly, in graduate school from 1988-1995. I wrote my dissertation on a Mac Classic (or perhaps it was a Classic II), using the version of Microsoft Word that existed way back then, and footnotes were added by typing apple-E. But since I veered away from scholarship into translation after finishing my doctorate, I have rarely written anything since then that called for footnotes.
This weekend, I'm translating an academic text with footnotes, and whenever I want to type a footnote, the old apple-E reflex takes over, and I end up with the text centered instead of with a footnote. It's not that I want to know what keystroke produces a footnote (I'm perfectly happy to go the Insert menu and select Footnotes). What strikes me is that this ancient reflex is still there, as it has never been over-ridden by a different reflex for generating footnotes or by a different use for apple-E.
There's probably a bit of deep psychology to be done here, but it's all just an anecdote really.