 When you switch between tasks, it comes with a cost. You're much less creative. You remember much less of what you do. You make more mistakes. So, yeah, Brian may not be totally far gone. He's not the equivalent of someone in a dive bar in North Las Vegas who just can't get through the next 10 minutes without vodka. But you will be, if you're using your phone very heavily, incurring those costs throughout the day.