>>2403707Not exactly. It was based on lessons learned from ww1 and 2 where patients might spend hours in a trench or a dugout before being stretchered to a first aid post and even longer before reaching a field hospital (with the tq often left on in the meantime).
There are serious risks with tourniquet application and they should not be used for no reason but if other methods of bleeding control have failed (or if you've got an artery spraying blood across the room, or if you're under fire and need to evac) then they're the best option.
If applied correctly then the risk of any complications (nerve damage etc) is pretty unlikely up to 2h and the risk of limb necrosis requiring amputation is minimal for a couple of hours past that. There are other issues (reperfusion injury, pain, potential worsening of bleeding if poorly applied) but they're a tool worth knowing how to use.
If you're interested, this article is well written and reasonably accurate.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2660095/ 
