Coup de Grace questions (multiple attacks)

[Branduil]

It doesn't really make much sense if you take it literally.

I tend to think that when someone is hit by "sleep," they're actually just stumbling around drowsily. Otherwise you really could just kill them immediately. If someone is sleeping, you coup de grace them, and they don't die, they managed to wake up right before the hit and dodge most of it.

 

[Jhaelen]

Alright, I thought of those--there are always exceptions. But no matter how much we want to follow the RAW, doesn't it make sense that if:

1) The victim is truly helpless (asleep, in a coma, paralyzed, tied up, or otherwise immobile),

2) Large or smaller in size, and

3) There are no magical or unusual effects at work, and

3) The attacker is not being attacked or rushed in any way, then...

...a Coup de Grace means an automatic kill?

How about no?
Now, even if I were taking my time to slit your throat while you were completely helpless, you wouldn't be immediately dead. You'd be fatally wounded, true, but that's about it.

And you aren't even a hero (or a monster) in a magical world where it's possible to raise the dead (and a short rest will heal any kind of wounds).