Taxpayers' money is being wasted by government departments' failure to learn from day-to-day mistakes and listen to staff concerns, a public spending watchdog said today.

A study by the National Audit Office found it too often took a major crisis or breakdown to prompt Whitehall to making changes – affecting frontline services.

"There is effective learning in departments, but overall the evidence also indicates that learning is not yet sufficiently embedded within departments' working practices, nor is it prioritised as much as it should be," the NAO concluded.

"Learning often occurs following a crisis or high profile failure, but departments will be more effective at learning when it becomes a more habitual aspect of everyday working practice.

"Until then, learning within departments will be constrained and failures will continue to happen, leading to avoidable waste, inefficient practices and ineffective services."

Rapid staff turnover, a lack of time for learning, a failure to communicate between sections and "ineffective mechanisms" to support learning were to blame, it found.

Even some efforts to improve learning had backfired, it added: "A proliferation of tool kits, guidance and other products ... have been useful but there is a danger of guidance overload."

The NAO said staff had to be made to feel "safe" in speaking up about failures, their ideas for improvements and rewarded for coming up with better practices, and public complaints used better to shape reforms.

Departments also needed to "institutionalise the systematic reflection on performance after projects, even if it means delaying moving on to the next project for a while".

Tory MP Edward Leigh, who chairs the Commons public accounts committee, said he was fed up with investigating failures caused by the mistakes time after time.

"It is obvious that government needs to get better at learning lessons from past mistakes," he said.

"Departments must understand that the best time to learn how to improve service delivery isn't necessarily after a crisis or large-scale project, but day in, day out.

"Before embarking on projects, departments should identify lessons from what has gone well or badly in the past. And they need to examine what has worked well for other organisations.

"More generally, they should learn from a whole range of sources such as trends in complaints or the views of frontline staff, who often know best.

"Discussing service delivery with those who actually use or deliver the service is not just a nice idea, it is indispensable to improvement.

"When government projects fail to deliver fully, fall behind schedule or go over budget, it is often a result of poor learning. It is frustrating to see the same mistakes being brought before my committee time and again.

"Good quality lesson-learning makes for better service delivery. Government departments must take it much more seriously."

A Cabinet Office spokesman said: "The NAO report makes clear that best practice is shared across the civil service every day and highlights numerous examples that have allowed us to improve the quality and range of services we deliver to the public.

"Many of the problems the report identifies have already been addressed, saving the taxpayer millions of pounds."