One could make the argument that amount of information to be exchanged in order to get a good assessment really is that small. If they mostly look at how you behave under pressure and whether or not you can still tell a consistent story (pitch your start-up), then you only need a couple of minutes. From what I've read, they judge team dynamic and character for the most part, only checking if you're able to think of a good idea because it would most likely change anyway.