I can understand where frequent flyers are coming from when they talk about the repetitiveness of the briefings, however people should realise that some features, such as slides, do differ between the airlines as well as the aircraft.
For example, I have operated A320 aircraft where, in a ditching, passengers are directed to the forward and rear doors (not overwing exits). The slide is used as a floatation aid and NOT a raft.
Other A320 aircraft I have operated required the use of the overwing exits only. What do you do when airlines have a mix in the fleet. This does happen.
You can't assume that every aircraft is the same, even within the airline.