New figures show almost a fifth of all police armed offenders callouts are in Canterbury - more than the three Auckland districts combined.
Data released to Radio New Zealand under the Official Information Act show that police were called out to more than 5700 incidents over a seven year period.
Between 2007/08 and 2013/14 the Armed Offenders Squad (AOS) was called out in Canterbury almost 976 times.
That tops the three Auckland districts, Waitemata, Auckland City and Counties Manakau, which had 844 callouts.
The district with the next highest number is Wellington, but that too is far behind Canterbury, at 756 callouts.
National Manager of Operations Chris Scahill attributed the numbers to the geographical size of Canterbury.
"Across the pan Auckland area, you have a far greater density of frontline staff who can quickly and effectively come together to deal with emergency incidents," he said.
"Whereas in the likes of Canterbury, being so large geographically, you don't have anywhere near the density or tight concentration of frontline staff."
He said it was more of a challenge to get the numbers to deal with any emerging incident, so the first port of call would be the AOS.
He said an identical incident in Auckland and Canterbury may be treated differently.
"It could be. Or in Northland, or in Southern, these large rural areas where you might have one frontline or two frontline officers who are faced with an incident that is simply beyond their capacity."
AOS overused - criminologist
But a criminologist at the Auckland University of Technology, John Buttle, wasn't buying that reasoning for the figures.
"I can understand for instance, in a rural area where police officers may be on their own patrolling more, that there is a greater need for backup because their backup is sometimes 25 minutes away," he said.
"But you don't need the Armed Offenders Squad for that, do you? You don't knock on someone's door with a bunch of blokes with guns when you don't need to."
He said the police should find other ways around that.
Over the seven-year period, the armed squads engaged in more than 5700 callouts throughout the country.
Mr Scahill said the demand for the squads remained steady but the nature of the callout work was changing.
"Fifteen to twenty years ago, you had mainly operations or AOS jobs mainly around emergency incidents such as violent domestics, robberies.
Nature of callouts changed
"Now, for example, because of the violent behaviour and the presence of firearms often associated with drugs manufacture, we're seeing a demand for AOS to be attending pre-planned operations."
Mr Scarhill said those operations include search and seizure warrants and account for more than half the work AOS now does.
But Mr Buttle said he believed the squads were called out too often.
"The police are kind of overusing the armed offenders squad and it would seem that Canterbury themselves are using more than anyone else.
"I find it hard to believe that a place the size of Canterbury would be using this more than Waitemata, Auckland City and Counties Manakau put together."
"It would seem to me that they're probably being a bit over zealous," he said.
The figures also show out of the thousands of callouts only 350 were prompted by a shot being fired before the squads arrived.
And in those seven years, six people and four dogs have been killed by police in AOS callouts.