I have the 921 and just read the instruction book.
https://www.allamericancanner.com/All-American-21-Quart-Pressure-Canner.htm
There is no advice to remove the lid quickly after it is cooled enough to remove the pressure weight. Sometimes, if I’m only doing one batch, I’ll let it cool overnight. Never had a vacuum form because the vent that the weight sits on allows air in, but also the black safety plug leaks air as well. I’ve noticed that as my canner leaks steam as it’s coming up to temperature around the black pressure relief plug. But once it’s up to pressure, that stops.
I just regularly check the temperature gauge and watch it while it’s processing. I never leave it unattended for the whole time of the canning. I’m always around listening for the rattle of the weight and occasionally checking the gauge.
“I’ll let it cool overnight”
Wow. I forgotten all the liberties we can take with the metal lids. That wouldn’t work with the toddlers, but it’s nice to know it can happen and no vacuum.
I’ve been going through the videos I watched to see where I saw to remove the lid quickly. I can’t find that one but I saw one that said wait 2 minutes after removing the weighted gauge. That’s not on the All-American website at all.
Looks like lots of video makers Are adding in unnecessary steps!
I’ll stick with the All-American pdf.