Each shipping company has their own way of doing drill, some you report to muster with your life jacket others you don't. Some muster in the lounges some on open deck.
The thing that is being missed is no matter how many drills you have for passengers when something really happens people are not in the right place, the ship does not burn as the book says, it does not stay upright as planned and some fool puts an iceberg in the middle of the Caribbean without permission or a rock in the way when the Captain takes the ship on a joy ride.
A life jacket will only keep your body afloat, it will not keep you warm.
They are not designed for jumping from a great hight 4.5 mtrs about 15 feet not from the height of a modern cruise ships promenade deck.
What the muster drill is really about is training the crew in what to do with a lot of people who need to be marshaled into places that they can then use to evacuate them from to the available life boats/rafts.
The life jacket in your cabin has numbers on it, from those you have a good idea if the worst comes to the worst of who is wearing the jacket, remember many will have no papers with them.
There are plenty of lifejackets at the muster stations.
The bottom line is life jacket or no life jacket you need to know where to go to get help and the crew need to practice how to deal with all those people in the event of an emergency.
The recent problem with the Costa Concordia was made worse by a Captain who was in denial of what he had done with his ship and should not be taken as the normal.
If you tune in to channel four UK TV on Tuesday night at 20.00 local UK time there is going to be a program about the recent sinking.