Quoted: "We make a lot of this stuff up as we go along," the lead designer said. Everyone in the group laughed until he continued, "I'm serious. We don't assume anything works and we don't like to make predictions without real-world tests. Predictions color our thinking. So, we continually make this up as we go along, keeping what works and throwing away what doesn't. We've found that about 90% of it doesn't work."