Like many things (upgrade lottery for instance) it seems like they change the rules AND implementation varies widely depending on gate agent. They REALLY need to pick a policy, advertise it, and have the gate agents actually learn and use it!
Talked to a GA in Atlanta soon after breezeway started and he admitted that it was a problem when they opened breezeway up at the start because places like ATL have SO many medallions that there can easily be 40 people mixed in with the actual first class passangers.
I *believe* the current policy is that they do zone 1 first and only, and THEN open up breezeway... But again seems like each gate agent does their own thing....