<i>Let me explain this concept using an entirely unscientific graph</i><p>Then he includes a bell curve with confusion on both outlying sides.<p>After reading so many black and white posts, "This is the right way," "Do it this way or I will kill you," or "That's lame," it's refreshing hear, "Use your judgment and find the sweet spot."  A bell curve is the perfect illustration.<p>Thank you, OP.  This is advice that applies to alot more than just UI Design.