The elected members updates are an initiative of incoming mayor Andrew King, who wants as much as possible to be accessible to the public.
King said the closed workshops and closed meetings did not work and under the new structure the updates would now be held in the chambers with agendas. It differed from committee meetings, as no voting happened.
"We had always intended it to be public and we didn't know it hadn't been advertised until this afternoon.
"If we have to discuss it behind closed doors - unless it's commercially sensitive, then should we be discussing it at all?"
"It will never happen again."
Councillor Dave Macpherson said even elected members had been unaware what was being discussed at Monday's meeting.
Briggs said he supported King's decision to make the meetings open to the public and would work to make sure they were given ample warning. He also planned to have the meetings on web cam.
Going forward only meetings that strictly met the requirements of the Local Government Official Information Meetings Act would be publicly excluded, he said.
"It is my ambition, and the ambition of the elected members, that it will be rare exception that meeting will be public excluded."
Under Julie Hardaker's mayoralty workshops and team meetings where housekeeping items were discussed were excluded to the public.