I took DL from MAD-JFK yesterday and there was no mention of the 1 hour rule. Just the usual 'please be seated for the remainder of the flight' and that was 20 mins from landing after the captain's announcements. ^ (All passengers had their hand luggage search in MAD prior to boarding, though).

I was also living in DC when it implemented no one out of their seat for the first and last 30 minutes of a flight into and out of DCA. A little irritating at times, and I'm glad it has gone.