I agree with your idea of private channels, but would also suggest that a naming convention for them is used. Public channel names cannot overlap with private

I agree with your idea of private channels, but would also suggest that a naming convention for them is used. Public channel names cannot overlap with private channels. One Slack community I'm active in wanted to add `testing` as a channel. But we couldn't, because that channel name was already taken as a private channel that was created before we locked down channel creation to the admins only. None of the admins were part of that channel, and we don't know if its still active to this day. As a result, we had to do `testing_`, with the trailing underscore as the differntiation. BUT when you do `#testing_` in the slack input, the channel name isn't hyperlinked. :-/