Mrs Blake, chief operating officer for Otago, and management leader of a special project looking at ways to improve emergency department stays, said it would not have been responsible for the cash-strapped board to make changes without validation.
She was commenting on a statement from the Association of Salaried Medical Specialists' Ian Powell, who said the results of the recent computer modelling confirmed what ED senior doctors had been saying for some time.
Planning for changes should have begun in 2009, he said.
He said "health bosses should have acted on the clinical advice when it was given," rather than treating specialists with disdain and "not have waited until the political blowtorch was pointed at them before acting".
Mrs Blake said she could understand the clinicians' point of view, but in a situation where the board had "very stretched resources" it needed to ensure that any action was evidence-based.
It would have been "dishonest of me" to put forward a proposal to spend considerable money to develop a unit without "base information showing where that would make a difference".
"I understand they have been voicing concerns for some time", but it was important that all worked together on improvements, she said.
The computer modelling, which had now been tried in three boards, was as "near as we can get to any evidence-based process", using hospital data to test scenarios.
The early results from modelling suggest reducing non-urgent attendances, a short-stay unit for patients needing monitoring before discharge or admission, and more staff cover at times, would shorten stays.
Mrs Blake said she hoped to have a report on a short-stay unit or medical assessment and planning unit ready for presentation to the hospitals' advisory committee in the next few weeks, after discussions with staff.
She pointed out that even with such a unit other measures would be needed and the "6 Hours - It Matters!" group led by herself and intensivist Mike Hunter was still exploring all other areas where improvements could be made.
Recently, their whole-of-systems approach had included perusal of the efficiency of the discharges process and difficulties in ensuring patients requiring acute surgery were treated in a timely manner.
