Unfortunately, I have some experience in strangling...
Me and my cousine was around 12-13 years old when we where playing and I had a leather cord that I put around his neck with the words "I'm an assassin" (don't watch movies

).
He said, afterwards, that:
"I just saw something pass before my eyes (it was the leather cord) and then I felt something constraining my neck/throat. A few seconds after that I saw black spots appearing that grew and grew and finally it all went black."
From my point of view:
I put the cord around his neck and pulled, he struggled for maybe 5-10 seconds (can't remember the exact time, it's 22 years since it happend) before he dropped to the ground. Naturally, I thought he was trying to fool me (like always) so I said i don't buy it, but he didn't answer (not that I expected him to do that).
When he woke up, after just a couple of seconds, he told me what happened and after that incident, we never tried to 'play assassin' again, that's for sure.
It went so fast I still can't believe it, but the cord must have prevented the blood to flow to his brain, and therefore cause the fast incapacitation that he suffered. Luckily he escaped unharmed from the accident.
So, if you strangle someone, you will probably not just put preasure over the throat, but also around the whole neck and therefore also prohibit the blood flow. Granted, a garrote is much more effective for that, since it will 'dig in' better, but I still think strangulation is underestimated in rpg's (I always remember what happened when me and my cousine played when I read the strangulation rules in rpg's and notice how ineffective they are, it takes forever to strangualte someone).
That was my thoughts, and some experience from me, hope it could shed some light on the issue ('cus it sure turned off the light for my cousine, hovever brief :wink: )