Survival trainer Stu Gilbert said the fact the two 23-year-olds were prepared to stay out in the bush for several days meant they likely had shelter and extra clothing.
He said having that protection and tramping experience, was a "game changer" for what otherwise could have been a very different end.
"The most vulnerable people that go into the bush are not the people that are heading in for a week or five days, it's those who expect to be out there for just a few hours or the day because they don't have the extra equipment one would take with them for multi-day tramps."
READ MORE:
• Trampers missing in Kahurangi National Park: Dion Reynolds and Jessica O'Connor found alive after 18 days in bush
• Trampers Dion Reynolds and Jessica O'Connor found alive in Kahurangi National Park; were out of food but search helicopter spotted smoke from fire
• Survival triumph: The 'incredible piece of searching' that unearthed missing trampers' location after 19-day ordeal
• Hopes dashed: Jersey found by search team offers no leads in hunt for missing trampers
Police have indicated Reynolds and O'Connor became lost early on in their tramp.
Gilbert said food was not a high priority in survival, with evidence people could go for weeks without it.
"The biggest threat to them in the last few days at least was the weather, because if they couldn't protect themselves from environmental conditions, then they've got an issue with the likes of hypothermia."
MetService meteorologist Cameron Coutts said the two trampers were "really lucky" with the weather.
The only significant rainfall forecast in the area was on May 24-25 where up to 100mm over that two day period was expected to fall, he said.
"Otherwise it was mostly fine for the rest of the time, just the odd showery spell, and on the fine nights probably fog and mist in the valleys."
Temperatures dropped as low as -8C about the tops of the ranges and there would have probably been early morning frosts at times in the valleys, Coutts said
During the day, temperature highs were in the mid-teens and there were no gale-force winds during the period they were in the bush, Coutts said.
NZ Mountain Safety Council chief executive Mike Daisley said Kahurangi National Park was the sort of environment people would usually only go into if they were really prepared, as these trampers appeared to be.
He said while it was "quite unpleasant" to go for a long time without food, exposure leading to hypothermia was a bigger threat.
Daisley said the trampers would have experienced a whole range of emotions.
"They would have potentially seen helicopters flying over in a search pattern looking for them and potentially not being able to attract their attention."
He said their rescue was great news and must come as a huge relief to their friends and family.
Both Daisley and Gilbert said this case was an example where taking a personal locator beacon on a tramp would have dramatically changed the experience of getting lost in the bush.
Reynolds and O'Connor stayed put soon after realising they were lost.
Outdoor Training New Zealand chair Heather Grady said this move would have been critical to finding the pair.
"If they're moving around, they may move into an area the searchers have already searched and so it's like trying to find a moving target. It's much easier for searchers to find someone who's staying put."
She said lighting a fire was a good way to attract attention from a long distance.
"If you are lighting a fire as a signal fire to be found, get it really good and then put green vegetation on it to make it really smoky."
Local Paul Kilgour has been tramping for almost 50 years and is very familiar with the area the pair were in.
He said the country gets steep quickly going inland and the vegetation gets scratchy in the valleys.
"It's very unpredictable country and very challenging if you're not used to it."
Kilgour said he felt quite emotional on hearing that Reynolds and O'Connor were found.
"This could be quite a survival story really for someone to be in the bush for two and a half weeks, and especially in the storm conditions we've had the last few days and in that country, this is quite remarkable."
