Urban legend. Not true at all. Nothing can kill a trip except time. Not even Xanax - it will just help you relax and kill the panic and anxiety.

The caffeine part is particularly bad advice, as a stimulant is the last thing you want to ingest when you are already highly agitated.

enough lorazepam and you're done

YMMV, and there's not a ton of research on this stuff, but I personally wouldn't go near any stimulant while being on any psychedelic.

This is pretty awful advice...

Xanax will be good for LSD, but really unnecessary for mushrooms.

I agree that LSD is more prone to producing 'freak outs' or acute psychedelic emergencies than mushrooms are, but disagree that having a benzo on hand is 'unnecessary' for mushroom trips - I have seen a couple mushroom experiences spiral out of control which could have been aborted by Xanax.

Ive had a freak out on shrooms myself. I just am very careful about Xanax/Benzos because they’re highly addictive. Xanax is kinda like alcohol, it's a gaba-ergic drug - it will help, but the primary way to stop freaking out is to calm down and breathe properly, and be assured that things are ok. But I’m sure in an emergency it can be useful.