Parrott - treadigraphs story about Bob Tuck agrees with the bits I've read - there was a constant 2 way flow of information up and down the commands - for example the squadrons were apparently warned about the existence (if not the performance) of Fw190 a while before it ever appeared in action
I don't think it as ever codified - it was just what good officers did - talk to the troops - although there were post op debriefings that were always written up of course