After a hectic trip to New York and Japan, Prime Minister Jacinda Ardern is on her way home. When she returns, Parliament will be in recess until October 14, giving her Government time to shore up its domestic agenda and sharpen its focus to tuck away a few key policy wins ahead of a general election that could be held within 12 months.

The problem with foreign affairs in general – and trips to international confabs such as the United Nations General Assembly in particular – is that it is a challenge for any prime minister to explain how they help improve the lot of the ordinary person. There can be a fine line to tread between making the country proud, and reinforcing tropes about free-loading politicians.

Even trying to negotiate a trade deal is tough – the concept is abstract and deals help people in aggregate. Even the best new trade deal is difficult to sell to the public immediately, because the benefits accrue over time, but any losers are quickly obvious.

Bottom line: it's tough to turn international trips into a political positive.

Near the end of her trip to New York, Stuff sat down with the prime minister to ask how she manages this difficult balance.

"It's fair to say from the moment I came into the job, I underestimated the amount of time and energy that has to go into the international work. But I think that's actually been true of any past leader I've spoken to," Ardern says.

"Because when you are in Opposition there's no mirror of that, you just do the domestic because there's no real call on you to have to do the international. But when you are away you keep the domestic wheels turning.

"So, you know, my Cabinet papers come to me still – I still get my advisory notes, I'm still staying in contact with everyone back home. So you just manage the workload wherever you are and ... no matter what you are doing."

The National Party has tried to make hay out of this particular issue, suggesting Ardern is a "part-time prime minister", who prefers meeting celebrities on the international stage to, in the words of leader Simon Bridges, doing the tough policy work to make things better for "everyday" New Zealanders.

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"I never feel like I've ever had to trade off anything domestically significant in order to pursue something like the Christchurch Call," Ardern says.

Yet Bridges clearly sees this as a weakness for Ardern, but he will have to show some judgment in criticising her. As a small, open, trading nation, international engagements are an important part of any prime minister's work schedule.

Creating a political environment where important trips are seen as frivolous could create a problem for National next time it is in power.

In any case, Ardern sees the distinction between international and domestic priorities as an artificial one.

"The international agenda for me is all about extending our domestic focus anyway. So be it the Christchurch Call, trade agreements, it's still all ultimately about New Zealand's interests. But with our values as well."

At the UN General Assembly, each country gets 15 minutes to deliver a "national statement". So to push this agenda, a lot of work is involved in crafting a narrative on the Government's plans to present to the world.

In reality, many speeches often go a lot longer, and can range from a basic update of each country's economic position, to a ramble. US President Donald Trump spoke for a boring 32 minutes, reading a speech someone else had clearly written.

Conservative Brazilian President Jair Bolsonaro rambled on about Cuban and Venezuelan socialist plots, opening Brazil to investment, before warning against the evils of gender-fluidity theory.

UN Secretary-General Antonio Guterres seemed to list just about every problem in the world and what the UN was going to do to fix them.

In this other-worldy forum then, how does a Kiwi leader possibly work out what to put in a speech?

"They take me a while," Ardern says. She mostly write her own speeches for big events, not a common practice around the world. And while must drive her staff mad at times, it shows when a speech is delivered: it is actually in her voice.

"It is really difficult." she says. "Last year I tried to cover quite a bit more ground but this year I thought 'well, actually, at this moment in time, what is it that I think New Zealanders would want to say on the world stage'?

"It felt to me like obviously given the number of New Zealanders who have stopped me and talked about when they've gone abroad, that March 15 in particular has been raised consistently with them.

"So I knew that I felt I needed to talk about that, but also because it's so climate-focused at this leaders' week just sharing a bit of New Zealand's experience as well.

"But otherwise it is hard, because there's so many things I wanted to add, on the Budget, the work we are doing on mental health, so you've just got to pick a couple and run with it."

In a pre-trip interview, Stuff asked Ardern last week what would constitute a "win" from this trip. Progress on the Christchurch Call, trade and climate change were things nominated. Ardern says that New Zealand has made progress in all three.

The Christchurch Call in particular, was a success.

"The fact that we now have a piece of infrastructure that will exist to take this work forward, for me is really important because, yes, we need to keep nudging along, but New Zealand can't do that on its own and our systems put the work in, but we now need it to keep going. And I'm confident that it will,' Ardern says.

As a result of the New Zealand-led diplomatic efforts, a protocol for governments and social media companies is ready to go in the event of another Christchurch-style massacre being live-streamed. The tech giants will also fund a new watchdog that will help them monitor and act more quickly if extremist content is spread online.

"To have prime ministers Scott Morrison, Boris Johnson, President Macron, King Abdullah– you know, the really diverse range of people who were involved in that – said to me that this was not just New Zealand's issue, and it was not just a solution that New Zealand needed but that everyone saw the need for."

On the other issues it is unclear yet whether or not significant progress has been made.

The prime minister says she and Trump talked trade: in particular tariffs, which New Zealand has to pay on aluminium and steel being exported to the United States. Australia has managed to avoid the same tariffs by effectively telling Trump that he is beating them on trade because they have a trade deficit with the US.

Trump believe trade deficits – where the value of a nation's exports is more than its imports – indicate losing at trade.

A good personal relationship with Trump is clearly a necessary – but not necessarily sufficient – condition to get to the front of the queue on these decisions.

The free trade climate zone talks announced – where countries will co-operate on reducing fossil fuel subsidies and removing tariffs of on green technology, among other measures – also appear to fit into the "wait and see" category. It is a worthy idea, but time will tell whether it amounts to much. Fiji, Iceland, Norway and Costa Rica will now negotiate the trade deal, so it's watch this space.

It is also worth noting that although these nations pointed to tariffs on parts of wind turbines and solar panels as something that can be freed up, four of the five countries generate the overwhelming majority of their electricity from either hydro or geothermal energy. Fiji is about half hydro; diesel makes up most of the other half.

None of these countries has to deal with the practical and physical – as opposed to ideological – problems of folding lots of unreliable wind and solar power into their energy grids while also keeping the lights on and prices reasonable. This is the problem that, say, Australia has utterly failed to even start dealing with.

Notwithstanding that, the prime minister has succeeded in miniature where the World Trade Organisation failed.

"I'm really pleased with that. To know that actually attempts were made to do that previously within the WTO a couple of years ago – but it faded away – means that we can reinvigorate something that there's an appetite for, she says.

Overall for Ardern, however, the big difference in New York this year, compared wit last, was the number of leaders who sought her out to express commiserations over Christchurch and pay tribute to New Zealanders' reaction to it.

"I'd like Kiwis to know that ... across the board I have had people stop me ... a dozen times a day to tell me that they noticed New Zealand's response to a horrific tragedy. But it was the response. They saw the compassion and the empathy of the New Zealand public.

"And I have felt so proud to hear some of the comments that world leaders from every corner, you know, be it Imran Khan or the leader of Iraq, people from across Europe.

"Without fail, people have mentioned New Zealand. So that's – inasmuch as it's been prompted by an absolute tragedy – it's also made me proud of New Zealanders."