> I'm curious, I was told most use cases of tourniques would require subsequent amputation.

This is very vague. I was trained to tie tourniquets for the limbs (arms and legs). I was taught that it takes a few hours before cell death sets in and about four until complete loss of limbs. This means that if you can get the wounded to a hospital (or a well equipped surgeon) quickly enough, you can even save the limb.

For other places like the abdomen and torso, the story is different.