I wouldn't want to be the guy to jump in without my air on in a GUE course!

That skill can be used too for when you have a failure on your manifold or a freeflowing reg. You can shut down the offending post and conserve your gas supply.

Up here you can have a reg freeflow from freezing in the cold water. Often times shutting that valve down for a while will let the reg thaw out and you can open the valve up again and be good to go ...