Auckland has been put on notice - get testing if you want to get out of level 4.
But Covid-19 swabbing numbers have been falling so fast in the city, some centres closed early at the weekend.
There were just 2592 tests in Auckland on Saturday, a tenth of the number some days early in the lockdown.
Ministry of Health said it wanted to see about 7000 tests a day to keep an eye out for any undetected Covid-19 cases that could cause the outbreak to keep going.
So far in Auckland that's not happening.
Te Whānau o Waipareira chief executive John Tamihere said one of its west Auckland centres closed at 1pm yesterday because there was no one to test.
Some days in this outbreak they had been open till 9pm to get the job done.
South Seas Healthcare chief executive Lemalu Silao Vaisola-Sefo said they have gone from about 1400 swabs a day to fewer than 200.
His team are baffled by the extent of the drop.
"With Delta being the way it is, it does worry me that we don't have enough testing - especially around Auckland - to tell us the real picture about what's happening on the ground," he said.
Aucklanders had largely stepped up when it came to testing in the outbreak - about 20 percent of people have been swabbed.
But Deputy Prime Minister Grant Robertson said it could not stop now.
He reminded the tens of thousand of contacts to remember their follow up tests and said New Zealanders everywhere should be getting tested if they have symptoms.
"Even if it's a runny nose or aches and pains, we'd like you to get a test," he said.
The country could not afford to be complacent about its falling case numbers - 20 for two days in a row - and needed only to look to Victoria who were on the road to beating Covid-19 when cases numbers rose again.
Victoria epidemiologist, New Zealander Tony Blakely, said complacency and some frustration at Melbourne's several long lockdowns were partly behind the rise in cases there.
High testing was essential to helping weed out any hidden New Zealand cases, and he's a big fan of sticking to the hard lockdown.
There was still uncertainty including some cases not yet fully linked to the cluster and community exposure still happening, he said.
"In the last few days I've been incredibly excited for New Zealand and envious of New Zealand. You're making good progress but you're not there yet. You need to keep that lockdown hard in place, especially in Auckland," he said.
It was essential vaccinations kept increasing, he said.
Director-General of Health Dr Ashley Bloomfield said there would be more surveillance testing in the next few weeks.
That meant going out to find Covid, rather than waiting for it to turn up.
It included at essential workplaces and testing those crossing the regional border for work - especially if Auckland's neighbours go to level 2.
It would not be testing at the boundary, but rather regular testing similar to that done for border or health workers.
South Seas Healthcare was carrying out surveillance testing at a church in Māngere and had a mobile clinic for contacts who were isolating.
In previous outbreaks, pop up centres have been set up at supermarkets, and have included asymptomatic testing.