People say all sorts of things, but if they don't commit to writing directions down, how are people supposed to know what the person really wanted? Also, someone might say one thing, until death becomes immanent, and then they realize they want something else.
I have written a formal, witnessed statement of my wishes, in the event that I'm unable to utter them. My physician has a copy; there's a copy in my desk-drawer at home, with my will.
I understand that different health authorities here have different policies on the registration and application of such "living wills". I have no confidence that if I get sick in the wrong place, my statement will even be noticed, let alone respected. Also, there's no reason why a paramedic coming to my home would know to look in my desk-drawer (I live on my own), and so discover that I don't want any CPR, ever.
And ultimately, these living wills are advisory only; medics can't be sued for ignoring them.
It's a bloody mess. I really hope I don't ever get demented.