I always try to finish up what I'm doing on whatever device before turning it off but I always turn it off. I don't know why they tell you to do certain things but if it helps the flight go smooth I will do anything. I don't want the pilot to miss something important because my cellphone or ds was on. I'm already freaking out about being on a plane!! Once a guy next to me had to be told various times to put away his iphone. I was so close to whacking him upside the head!!!!