Last week at MSP DL had a bad MX on the 777 going to HND. It would have been worse if they hadn't swapped planes with the CDG flight, also a 777 but scheduled to leave about five hours later. However, the swap meant that the CDG flight was delayed too. These were departures on Wednesday July 3rd. It wasn't an instant solution as catering had to be moved over (as well as luggage) and some people complained that they had left slippers etc. on the original aircraft.