How effective is the tourniquet method?

[ChronicPainExistent]

In The Last Five Acts, I read that you could use the tourniquet to compress the carotid arteries, inducing a quick loss of consciousness. It seems to me that this method could be quite effective and even relatively pain-free. However, I haven't really been able to find much mention of this method. It doesn't seem to be that common. I am wondering why this is the case?

 

[Praestat_Mori]

Imo it's difficult for many to find the right place to compress the arteries and you have to overcome a lot of SI to tighten the tourniquet by your own hands.