The way we build stuff at Apple is often this way. Even the number of models we’d make of a new notebook or iPod. We would start off with a version and then begin refining and refining, doing detailed models of the design, or the buttons, or how a function operates. It’s a lot of work, but in the end it just gets better, and soon it’s like, “Wow, how did they do that?!? Where are the screws?