.. the only problem being that, if you're in a plane with actual life-vests under the seat, the seat cushions might not be easily detachable as they're not the primary flotation device. Also, is your life-vest located under your seat or in the bin above you? If it's under your seat, can you *reach* it?
I fly canadian airlines, seat cushions as floatation devices are not legal here, so the life vest is under the seat, always. and yes, I can reach it.
More-importantly, which of the exit doors are the kind that swing in and stay there? Which ones come completely off and need to be tossed out the doorway? Do you pull the door into the cabin from the top or bottom? Which doors release by swinging a single arm? Do you swing it up or down? Which ones don't have an arm, but a pull-down lever? Which of those have an additional cover over the lever which you must pull down *first*? Which doors should you not open in a water landing? Which doors have escape-slides? Which ones auto-deploy when you remove the door? Which ones require a tab to be pulled? Which ones detach to become rafts? How do you detach them?
Even more importantly, show me even one airline that includes that information in their safety briefing. (which is what this is talking about, not the seat card) (though I can tell you, the ones in exit rows over the wings you need to pull in and up and then throw out of the plane, they come completely off, you pull from the top. The other doors, and on planes with exit aisles instead of exit rows, swing outward, you use the big lever on the door, they all have escape-slides, and you can use all of them in a water landing, and they all auto-deploy when you open the door (assuming the flight attendant properly armed the door when the instruction to "arm and cross check" came over the PA)