I think if you were optimising the goals of a touch screen keyboard, your focus would probably be in minimising mistakes, and you'd end up with different sized

I think if you were optimising the goals of a touch screen keyboard, your focus would probably be in minimising mistakes, and you'd end up with different sized keys. I doubt you'd end up with Dvorak. I'm also highly skeptical that your muscle memory of a real keyboard helps much with a phone keyboard. At best it helps you know where the keys are - but they're already shifted a bit to deal with the smaller space.