Oh dear.
I know the take off emergency brief off by heart and I can recite the engine failure drill from memory. I hear it every day I go flying, but when the other guy briefs me I put down the paperwork and listen to what he has to say. As others have said, it keeps it fresh and will save me valuable thinking time should we ever have a real emergency.
Few things wind me up as much as pax who can't be bothered to listen to the safety demo.