I honestly don't get it.... As a passenger, it is quite simple.
Flight mode as you walk to the aircraft.
Then off.
Then on again when permitted you can so you can play games / read / music etc.
Then off again when told.
Then on and f/m off when you have cleared passports and customs.
It seems so simple, and really winds me up when others seem incapable of following some quite easy instructions. Do they honestly believe that they are so important that they simply ~must~ have their phone on at all times?