The criteria for what should be excluded was "fairly cut and dried", Mr Booth said.
Council staff reviewed agenda to identify items that might need to be discussed without the public and then brought these to him for approval, he said.
"They will identify what needs to be excluded and then they come to me and have a discussion with me ... It's pretty black and white as to what should be in there and what shouldn't be."
The 5 per cent target was set by council, Mr Booth said.
"It's what we'd like to have but sometimes it's not possible to achieve exactly what you'd like to have. In an ideal world there would be nothing in public excluded, but there's no such thing."
Councillor Mike Palmers said he believed all the issues discussed with public excluded were appropriate, but too many issues were discussed in the council-only workshops held before the meeting.
"I don't like the idea of so many things being caucused before the meeting because the public don't get to see the debate. I think it's a case of too much being workshopped and that has become an effective tool of excluding the public ... it doesn't allow the public to see the council and councillors and get an opportunity to see where they are coming from."
A collective position was often reached during these workshops, Mr Palmers said.
"I don't think it's fair to the public because we are their representatives and I think the public wants to know and understand the views and positions of their representatives on different issues."
Workshops normally ran for several hours before the meeting, he said.
"And that's why council meetings are so short because we've already done two and a half hours of council meeting things, effectively."