By Susan Edmunds, Money Correspondent

Long school holidays might have been important for the 19th century agricultural economy, when children were needed to work in the fields.

But in the 21st century, there are warnings that all that children are managing to harvest on their holidays is a lot of stress for their parents.

As school holidays start around the country, thousands of parents are trying to work out how to juggle work and school holidays, when kids get at least 12 weeks off during the year and adults only four.

Ellen Ford - author and founder of the #WorkSchoolHours movement - said it was a major problem.

"The hours of work, roughly 40 hours a week, 9-to-5, 48-ish weeks of the year... all that was cemented more than a century ago with the

Henry Ford car manufacturing era. That was amazing social progress in its time but it assumed every household had one worker and one caregiver of the children.

"That's just not our society today and it hasn't been for many decades. It blows my mind that we've gone to the moon, we've invented the internet, we've got AI but the construct of work genuinely hasn't changed in the last century, it's an enormous mismatch."

She said it meant there were some households where it was not cost-effective for both parents to be in work, or for a single parent to work at all.

That could mean someone was at home and out of the workforce, not by choice.

"The cost of childcare often doesn't stack up, especially if you're in a lower-paid role."

Mother-of-two Sarah Campagnolo said she often managed the juggle by taking turns with her partner to work from home. But then that could mean her kids spent too many hours on screens, she said,

"We encouraged them off screens, of course, but when you've got a tonne of work to do, you don't have the time to parent your kids through their boredom. You need to work and you can't have kids fighting in the background or moaning about being bored."

She has spent the past year training to be a teacher. While it was not the only reason, she said the opportunity for more flexibility in the holidays was a drawcard.

Ford said some people put their children into holiday programmes, even if it meant that the household was making a loss during the holidays.

She said the #WorkSchoolHours movement was not saying that people should never work outside school hours, but was encouraging employers to focus more on output, not the number of hours worked.

"I speak at events and run workshops helping people implement this stuff and the businesses that do best are the ones that treat people like adults. They say 'we know you've got stuff you care about beyond work, we've employed you to do these tasks, we're less fussed about when, where and how you do them."

She said many people just needed a bit of flexibility. "I do work a bit during the school holidays, maybe in the evening when the kids have gone to bed... flexibility is the biggest key to allowing people to deal with the things they have on beyond work. In many cases, that's the massive juggle of kids and work."

It can be harder for people who do not work "laptop jobs" to have flexibility, but Ford said she had seen it work in manufacturing, farming, retail, hospitality and nursing.

When people had to work during the school holidays, offering some flexibility and input into shifts made a big difference.

"A dairy farmer I worked with did the milking schedule around the school bus. They acknowledged people in the community will be milking cows, they have kids they need to get to the school bus and pick up after the school bus. It's incredible for staff retention."

She said her research indicated that when people had "a taste" of flexibility, it was very hard to go to a job that did not offer it. "It's a massive part of a remuneration package."

AUT research in 2018 showed that two-thirds of respondents said they had conflict managing school holidays. Sixty percent said the holidays made it challenging to focus on work and achieve their normal performance. Almost 70 percent said they did not feel like a good parent during the school holidays.

NZCTU policy director Craig Renney said New Zealand had expensive childcare and long working hours compared to other countries.

"We should be looking at ways of making support for people in work easier and simple and cheaper."

There was a risk of bifurcation in the market, he said, with those who could work flexibly getting the benefits that accrued with that and those who could not suffering.

"We know when the holiday seasons are for children, a bit of compassion probably goes a long way to help."

The Ministry of Social Development offers a subsidy for holiday programmes, depending on the number of children that a family has, and household income.

A family with two children earning less than $1221 a week gross can get up to $319 a week. The amount drops as income grows, when a household earns $2401 to $2578.99 a week they get just under $100. Above that, there is no subsidy available.

A full day at a holiday programme can be $50 or $70.

Frog Recruitment managing director Shannon Barlow said it was probably less common at the moment for employers to offer holiday flexibility.

"The market has changed so dramatically. Employers probably can't afford to offer extra time off and also feel they don't need to go the extra mile to attract or retain staff." -RNZ