On a busy squadron, the authorising officer can't attend every crew brief. The out brief is a summary for the duty auth. Simply put, it works. The "dressed to survive" question was my favourite. Pilots trying to fly in winter without the basics to last 10 minutes outside the aircraft!
The out brief works particularly well in the police/AA civilian role where there isn't any time to plan.
When you leave the house you self out brief....... Keys, wallet, phone......