Speaking to a Canberra audience of senior public servants recently, former Commonwealth Ombudsman Michael Manthorpe, who spent more than four years in the role until this year, said it was an important oversight mechanism to establish, and soon.

"While the vast majority of people I've worked with, are in my judgment, honest, I hope that the current debate results in a strong, effective, fair and enduring integrity system that builds public trust in institutions," he said at an Institute of Public Administration Australia event.

Many of the major stuff-ups Mr Manthorpe had seen in the public service over his nearly 40-year stint did not come from poorly-formed judgments, isolated mistakes, moments of incompetence, or deliberate malfeasance, he said.

Instead, it came from groupthink and teams in window-less silos.

"Most of the stuff-ups are the product of multiple instances where problems manifest in a course of action in policy design or delivery, but the responsible officials don't, wont or can't see it, even when people are pointing out the risks," he said.

"Most of the stuff-ups are because over a period of time, teams, divisions, departments, sometimes ministers get so convinced of the virtue of their project, that they're the opposite of curious."

During his time in the role, the veteran bureaucrat took on issues with the immigration system, challenged the expanding roles of intelligence agencies and wrote damning reports on bureaucratic failures.

But he accepted there was a limit to helping those who had to come to his office with genuine complaints worthy of further investigation.

Months earlier, the watchdog was criticised for refusing to release robodebt minutes, which would outline what advice then-social services minister Scott Morrison was given and how he chose to respond to it.

The government watchdog said it received the minutes in early 2017 but would not release them because it threatened to affect their ability to oversee departments and agencies.

It added its role was predicated on "almost unfettered access" to information and documents from the agencies and that required discretion to maintain trust.

It said it also did not have the power to compel agencies to hand over documents.

Mr Manthorpe on Friday admitted his hands were often tied because the oversight body lacked stronger powers.

"The Ombudsman can't change policy or legislation. The Ombudsman's lane is administration, not policy," he told senior bureaucrats.

"And even when an agency should plainly be doing something differently to help the hapless complainant or countless others, the Ombudsman can't make them do so.

"So, the Ombudsman sits in the realm of influence."

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But despite the journey not always being easy, Mr Manthorpe said he would do these past four decades again if he had the chance.

"Things will go wrong. You will be disappointed not to be promoted. You'll be unhappy about how your great policy idea doesn't get up. You will put in a subpar performance in front of your minister, or a parliamentary committee. You'll be convinced of the need for more resources only to have them cut," he said.

"And in response to those sorts of things, I learned this critical lesson: it's what you do next that counts.

"Reflect, seek advice, learn, adjust, keep going. Work on ways to build your resilience. Keep an eye on your mental health, and try to keep these things in perspective."