Yes, I have sailed twice with Carnival - the Jubilee and the Triumph and was terribly disappointed that the muster drill was held at the time of the sail-away. I remember hearing the loud horns as we set sail while we were jammed side by side in the drill area downed with lifejackets....just stupid because you couldn't hear the staff give the instructions and when they did, they had to stop/start due to the horns blowing from above. In addition I thought it was hazardous for all those people to be crammed into one area while all the luggage was stacked all over the floor ready for the crew to distribute it to rooms....another hazard.
I think they should do the drill (without the life preserver) - simulation by the crew staff while you wait in line at the registration. For the 1-2 hours as you wait, they have your undivided attention. I think the passengers would be more attentive, less distracted and would learn the procedure.