New Zealand's quarantine-free travel suspension with NSW is over, coming offline at midnight on Sunday.

New Zealand has been urged to fine-tune its approach to the trans-Tasman bubble after a border closure "overreaction" last week.

New Zealand suspended quarantine-free travel with NSW for three days in response to the discovery of two community cases in Sydney last week.

No other Australian states took the same approach.

NSW Premier Gladys Berejiklian called it an "overreaction" and that the "response should also be proportionate to the risk", given it was just two cases from a city of over five million.

Australian National University Professor Peter Collignon agreed, citing NSW's strength in contact tracing meant the risk was "very low".

"It's not zero but it's never zero because you can never know," he told Radio NZ.

"All those people should be in isolation so that should mean there's not a risk to the community."

The government made the pause in line with its traffic-light-style framework, which says cases without a known source should bring short-term suspensions.

University of Otago epidemiologist Michael Baker said he was a long-term advocate of the traffic light system but being out of step with Australian states showed New Zealand was too cautious.

"We're thinking about Australia like the rest of the world which it isn't. It's very very low risk. The risk is absolutely miniscule," he told AAP.

"You'd expect responses to be broadly similar and the thresholds to be quite similar.

"Perhaps we could take what we learned from these and say can we adjust our response?"

Mr Baker also said there wasn't a case to lock down an entire state - capturing places like northern NSW, hundreds of kilometres away - with such localised cases.

Prime Minister Jacinda Ardern defended the decision to lock down an entire state, saying it was "proportionate" to a January call by Australia to lock down, a decision she attacked at the time.

"From time to time we might take that precautionary approach in the same way as Australia did with our Northland case," she said.

Ms Ardern said locking down regionally was likely to be too difficult "because of the systems we have at an airport".

"That does really rely on almost declarations by people at the gate ... that's not a great way to be making those public health judgments," she said.

New Zealand has also been criticised for its tardy decision making.

COVID-19 Minister Chris Hipkins announced the border closure 26 hours after NSW publicly revealed the first community case, with flights not blocked until 40 hours after the announcement.

Also on Monday, Ms Ardern announced changes to NZ's allocations of quarantine hotel spaces on Monday, with critical and seasonal workers, international students and refugees to be granted places.

Mr Baker said the government should consider further bubble arrangements similar to Australia.

"I'm a big fan of Taiwan coming on board very soon because they're the world leader in managing risk," he said.