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A Families Commission study has found children of separated parents are better off if they either see both parents frequently or barely see one parent at all.
The study has found seeing dad only every second weekend - traditionally one of the most common patterns - actually makes the children more distressed.
Study author Jan Pryor said that pattern was changing, as both mothers and fathers realised their children needed to have ongoing, close relationships with both parents.
"I think that default of every other weekend is disappearing to some extent," she said.
"There is good research that shows that is about the worst thing you can do to kids, particularly young children."
The study is based on interviews with 39 separated parents from 31 New Zealand families.
It is the first stage of a major project in which the Inland Revenue Department has invited 10,000 separated parents to take part.
About 1600 parents have responded. Results are due out early next year.
Ten of the 31 initial families shared care of the children, both parents having the children at least 30% of the time.
That is a much bigger proportion than in similar studies in Australia, which have found the number of separated families where both parents have the children at least 30% of the time has risen from 4% in 1999 to 10% in 2006.
Another 12 of the New Zealand families had arrangements where the non-resident parent had the children at least every second weekend, and nine had less frequent arrangements.
About half of all New Zealand children are believed to be affected by parental separation, including 20% whose parents separate before the child's first birthday.
The clinical manager of Man Alive in Henderson, Jim Heays, was one of the 39 parents interviewed and said he learned to be more involved when he went through his second separation 13 years ago.
"I've been through this twice. My older kids are now in their early 30s," he said.
"I made a lot of mistakes that time around. There was a lot of emotion flying at that time, and a lot of hurt and stuff that you have to work through, so the kids often came second-best."
With those children, and with the son of his second marriage William, now 14, he initially agreed to have the children every second weekend.
This year, the arrangement has reversed and he now has William with him in Auckland for the sake of the boy's schooling, and William goes back to his mother in Northland every second weekend.
Dr Pryor said the evidence internationally was that what mattered for children was stability.
"There is a very good study from the States showing that if kids saw their father weekly or more often, they were in good shape, and if they saw him not very often, they were in good shape, but if they saw him only once or twice a month, they were not," she said.
"Particularly for younger children, 12 days is a long time, and then they just get to know that non-resident parent for two days and have to go back again."