Official papers reveal the police made a number of operational mistakes during Easter weekend two years ago when 12 people died on the roads.
That weekend, which was the worst Easter road toll since 1992, ultimately led to a four kilometre per hour speed tolerance being introduced for future holiday periods.
A Transport Ministry report says a review found that police misjudged the risks inherent in a holiday period and it appears Easter was treated as business as usual in many districts.
Key police tools such as operation orders were not issued and intelligence products not well used.
Many staff were not working, with holiday provisions causing tension between managing leave and costs, and balancing demand and risk.
The acting national road policing manager, Acting Superintendent Rob Morgan, says he does not believe the report highlights operational mistakes.
"Police were out there doing what they normally do. Really, it just highlights the fact that police could have done some other things differently."
Mr Morgan says those things, such as the lower speed tolerance, were identified and have been part of campaigns since mid 2010.
The Automobile Association says it is disappointing police did not do everything they could have, but supports the significant resources and effort from police on subsequent holiday weekends.
The Green Party says it is no surprise that there were issues around managing police leave, as the road policing budget was under pressure then and still is.