I'm no longer crew but PEDa would cause so much grief.
My personal favourites were people who turn their decides face down when asked to turn them off (no that doesn't turn them off!) or those who argue that kindles are not electronic (well they don't run off of fairy dust do they?).
I used to incorporate switch off procedures for iDevices, Android and Kindles into PAs just to reduce the time taking to secure.
I'm glad I'm out if it now because I just know polite requests will be met with "well British Airways let you".
EXXB - it's when walking across the apron that it is prohibited to use mobile phones as the aircraft or the aircraft next door may be being fuelled in the same way petrol stations advise against the use of mobile phones. That PA was part of the disembarkation PA when I worked there so it's been out there for a good while.
As for being 20mins out I remember when I worked at EZ cabin secure ten minutes was the norm however in some places it would be sooner as pilots need to anticipate the likelihood of a shortcut and GVA can give quite a large shortcut, so cabin is secured in anticipation of this. But having prepared for the shortcut you're often sent downwind and it takes a while to get on the ground. Safety and getting the cabin co secure on time is the priority there. Milan was another one.
I do like gate-to-gate PEDs. I used BA the other day and it was great. I cannot wait for it to become more widespread.