lickily: From what I observed
on two recent AlaskaAir flights, three hours is probably not enough time to efficiently utilize the "DIG."
They are not practical in coach during a meal/snack service because there is simply no room on the tray table for the device. In first class, with the larger seat and tray, they were in use, however.
Given the fact that the first and last twenty minutes of each flight were "flight attendants seated," and given the amount of time spent on the first beverage service and meal distribution when flight attendants are otherwise occupied, I doubt that there is an uninterrupted two hours for player usage on anything but a transcontinental flight.
