restaurant industry. In short, a popular restaurant compared surveillance footage from 2004 to 2014 to find out why customers were complaining about longer wait times. It all came down to one thing - customers using their phones once they get seated. The average dining time in 2004 was just over one hour. In 2014, it was just under two hours. And the only variable was smart phone usage.

http://www.ijreview.com/2014/07/160051-one-restaurants-study-wait-staffs-service-reveals-unsettling-reality-time/