I think that's the point for a lot of emergency training (and 'refreshers'): so that when the alarms, or flames, or H2S sensors go off for real, or when you see an electrified coworker (grab something non-conductive instead of the coworker) or someone who's bleeding out, you don't completely freeze up, or only hesitate enough to evaluate.

Like how Gretzky (and others in that elite-amongst-elite tier of athletes) claimed they felt they could slow down time enough and make plays and analyses that the rest of us (and even many of their very-well compensated teammates) would just blink through.

And on the dark side... Before the mass murder / suicide of ~918 people at Jonestown happened, there'd been multiple "practice runs" prior with unpoisoned drink:

https://www.sfgate.com/news/article/Utopian-nightmare-3060346.php

Heck, maybe his followers wouldn't have suffered as much if they weren't even told. But I guess Sunday picnics ("try the punch!"--or more insidiously, here's the "communion wine") aren't really compatible with paranoid cult leaders whose cults face apocalyptic ends to their supposed utopias.