I once held one of those clowns selling floating balloons at gun point. Forced him to swallow the helium from all his balloons, one after the other. His make up dripping, tears running down, slowly inflating until he could no longer stay in ground. He squeaked for mercy, but I had none. He floated away and into some powerlines where he burst up in electrical flames. The police ruled it a suicide.
So all that to say, it's been falling from favor in contrast to nitrogen due to availability from what I've heard. I think the exit bag was more a helium thing early 2000's before there was more crackdown to access high % helium cannisters, which is not imposible but in the US a lot harder. So yeah you assume right that it has worked in the past, you'll probably get more current experiences with nitrogen. I still know some ppl here who have helium currently.
Can't offer much help, haven't experienced this myself.
Sorry you had to be here and asking about this in the first place, whatever has brought you to it, hope you didn't mind the clowing and that you have some easier days your way, hugs <3