Giving your players a time-out at the right moment
You know that place in Dragonball, the time temple near God that gives a fighter 1 year of training for one day outside ?
I kinda did this for my players.
I gave them permission for the full week to interact through roleplaying on the Discord channel of roleplaying as if it was happening instantly.
Why ?
Because we were at a very very very important crossroad for everyone and there wasn't a single second to discuss it at the start of the next session, which was starting with a battle that included 4 dragons, one of which was an ancient red.
And... well, it's both important and just fun to discuss in character of what to do when shit hit the fan, especially when you see a few ways the whole campaign could go to and you don't know for sure which is the actual good one for everyone.
It worked... sorta. Not everyone was on the same side, 2 of them prefered to leave the group and 2 joined with the bad guy that was their boss at the moment. And since the direction the campaign took then didn't really satisfied anyone, in the end I retconned before the very first big "oh no" happened.
But yeah, that metagaming bubble is a tool I'm glad that I have used, even if the result wasn't perfect. Highly recommand it, if you want to give your players a small hiatus of talking between sessions.
I don't stop them, I even created them a channel for it to do so. But doing it in a near-instant moment, where the character wouldn'T have time to do it, is in bad tastes for us ingame. Basically, if it's impossible to do it, then it's normally not something we do, and I don't need to ban it myself my players do it themselves.
Out of game, they can do as they please I don't mind. I even enjoy it.
Thanks for the clarification -- that makes more sense. It's interesting that your players police themselves on that. You must have a very respectful group!
My players chat and metagame between every session. I don't mind so long as they run any significant shenanigans by me to see if it would work. As in not too game breaking. I encourage it as it makes them feel part of creating the story. Ultimately the dice will tell the tale.
Like the OP, my players are pretty strict with meta information.
I had three parties step into the same trap and die and I was like "guys, what's going on!" and they were like "our new chars don't know what our old chars knew!"
I was satisfied with that. In the end made PCs quick-witted enough to deal with the situation without meta knowledge.
I've said they are free to meta as much and as little as they want, it's a lever they're completely on their own for, I don't mind it at all but to the extent that it takes away from their experience, they don't do it. I have two exceptions to this:
Don't do it in PVP situations. That's the one time you really must stick to your character only knowing what your character knows. I've put the kibosh down when they've been like "but I do suspect they're sneaking up on me", I've been like "dude—you flubbed your check! You don't know!"—I'd never do that for a monster but I did and would for PVP.
Don't read the module. Obviously. That'd be a group-firing offense. After we're done I'd be happy for you to check the module, but right now the only reason we even have me be the DM is so there can be unknown info to discover. Otherwise we could just whip out Mythic or Starforged.