[M]ost things simply respond automatically, like content width responding to text size changes; some things need to be modified like the Profile header, which would take up half the screen on a large device if we didn’t modify the layout; only a few things need to be rethought, like Direct Messages, where the list of conversations can sit side-by-side with the conversations when you have a wide enough screen.
Mike Davidson on Building a more unified Twitter for iOS
