I agree with "war rooms" not being as effective...but whiteboards, standups and deep dives personally can be helpful.

I think the key thing for me is that I never force people to sit in on these.

When an employee starts a large piece of work they don't understand that I feel have some knowledge on. I ask if they would like to whiteboard a solution with me...or deep dive something in the code, or do daily standups just to talk about w/e is on their mind

Doing these remotely is totally fine, but I do feel these activities...or atleast whiteboarding and deep diving is nicer in person for me