Child of a Metal God

That's a pretty neat point. I wonder if there's a specific axis along which people tend to be off, or if you actually want to surround a given key with its least likely compatriots. I mean, with touchscreens you're going to have skew along one axis, I think, probably running along whichever direction people tend to orient their fingers, since it's hardest to correct for mispositioning that's obscured by one's fingers, so thumb-typing has pretty clear shadows to the bottom outside corner on each half of the keyboard, divided by a vertical line, but for people who finger-peck on an iPad there may not be a clear problem area for each key.