What do daylight saving, Paul Henry and Home and Away have in common? They all have the ability to make us tune in or tune out; to make or break a network's ratings.
Data compiled by Nielsen Research, showing the average monthly audience across daily news and current affairs timeslots since 2010, reveal some fascinating insights - and worrying trends for our biggest newsmakers.
The data reveals a growing chasm between rivals One News and 3 News, particularly in the key commercial demographic of 25-54, as TVNZ experiences a fresh surge in popularity.
It shows the power of Paul Henry and his ability to bolster news ratings across multiple timeslots - and the devastating effect his departure had on Breakfast in 2010.
And it shows a nationwide decline in late-night viewing, with both networks steadily losing late news viewers year-on-year.
It also reveals the impact of major changes to programme line-ups - and an ability to turn ratings around.
As media commentator and former TVNZ news boss Bill Ralston says: "Things can always turn around. If we go back into ancient history, there was a period where the Holmes show really went off the boil and looked dismal. People changed the format and it went up again and came back strongly."
At TV One, Breakfast and Seven Sharp have both weathered the storms of change to see positive growth.
Now, TV3 is hoping to follow suit as it completes a total overhaul of its daily news programming. The launch of Story this week follows months of upheaval, which has seen the launch of Paul Henry (April), Newsworthy (June) and Story (August).
With our data set tracking progress until the end of June, it's still too early to tally any wins or losses for the new schedule. But already, Paul Henry is showing an upward trajectory, while insiders are hailing the launch of Story as "a fantastic result".
It debuted on Monday night to an audience of 293,000 viewers (115,000 aged 25-54), which fell back to 267,000 last night (100,000 aged 25-54).
TV One's Breakfast ratings peaked in 2010 with Paul Henry and Pippa Wetzell dominating our screens. With TV3's morning programme Sunrise cancelled in April 2010, Henry and Wetzell went unopposed for six months until Henry resigned from the state broadcaster. The effect on ratings was immediate and the data shows Breakfast has never experienced the same level of popularity since.
The following year, TV3 introduced competition in the form of Firstline, hosted by Rachel Smalley. She faced off against a new Breakfast line-up featuring Petra Bagust and Corin Dann, which experienced a sharp and sustained decline in ratings. In May 2012, Dann stepped down from his Breakfast role, to be replaced by current host Rawdon Christie.
Co-host Petra Bagust followed suit in December 2012, leaving Toni Street to take her place on the Breakfast couch, marking a turnaround in ratings, which continued when Alison Pugh took over in early 2014.
But TVNZ news boss John Gillespie warns against linking ratings directly to presenters.
"As with all shows, presenters are just one part of the mix and ratings can't be singularly pinned on two people - although they are certainly a key part of the overall dynamic equation."
Over on TV3, Firstline's ratings held steady through to mid-2012, when they began a slow decline, which continued until the programme was replaced by Paul Henry in April.
Once again, Henry delivered an immediate ratings boost, lifting viewership back to 2012 levels with numbers continuing to build.
Ralston said it remains to be see how far Henry's ratings will climb.
"Paul Henry's projection is going up but he's got a big gap to close there," he said.
"Breakfast is holding on but Henry's beginning to make a march. We won't know for another three months yet whether he's making significant inroads."
Meanwhile, Jennings is confident the programme will continue to build audience: "We are definitely seeing growth and we are going to get to a point where we are real challengers."
He says Henry is a rare talent who has the ability to "turn the dial".
"I think he will win that battle."
It's a huge number of people and a lot of money in advertising. If [TV One] can maintain that gap over the coming year, it's worth tens of millions of dollars, if not more, of extra advertising revenue.
The most striking trend revealed by the data is the seasonal nature of news viewing, particularly on TV One. Ratings spike during winter months and drop significantly during daylight saving.
Traditionally, 3 News has mirrored this pattern. But 2014 saw a drop off in 3 News viewers, with an even bigger decline this year. The slump is widely attributed to the loss of Home and Away, which screened at 5.30pm on TV3 until August 2013, when it moved to TV2.
The move came when TV3 entered receivership, allowing TVNZ to poach the popular soap opera from TV3.
One insider described the move as having "crippled the news bulletin".
Jennings admits it was disappointing to lose the Home and Away lead-in but says it's time to move on.
"You have to live with that. We're concentrating on what we can do. If we keep worrying about the lead-in that's not going to help."
Meanwhile, One News has seen a surge in viewers, with 2015 delivering its strongest ratings in the 25-54 demographic since 2011.
Ralston says the growing gap will be of serious concern to TV3, with serious financial consequences.
"It's a huge number of people and a lot of money in advertising. If [TV One] can maintain that gap over the coming year, it's worth tens of millions of dollars, if not more, of extra advertising revenue."
Another insider believes 3 News is suffering from a lack of critical marketing support.
"MediaWorks has sunk all this money into reality shows at the expense of marketing its news ... There is no money left in the tin to promote it."
No timeslot has seen more upheaval in recent times than 7pm. The coveted prime timeslot is critical to delivering audiences into networks' evening programming and both TV One and TV3 have made bold changes to their line-ups in recent years.
TV One was the first to blink, announcing the end of Close Up in 2012. At the time, the programme had witnessed a significant decline in ratings, particularly in the 25-54 demographic.
The following year, the first incarnation of Seven Sharp launched, fronted by Alison Mau, Jesse Mulligan and Greg Boyed. Ratings declined even further, with Campbell Live closing the gap between the two networks.
At the end of 2013, TVNZ reset the programme, bringing in new hosts and a new producing team behind the scenes.
As Jennings says: "Only TV One could have survived the Seven Sharp debacle. That was about as bad as it gets. But they adapted and came out of it."
In April 2014, Jesse Mulligan stepped down as host, leaving Mike Hosking and Toni Street to present the show as a duo. Ratings surged, while Campbell Live's audience tapered off.
This year, news that Campbell Live's future was in jeopardy saw a considerable spike in ratings, although they still didn't match the highs of 2013.
Seven Sharp also witnessed a spike following Campbell Live's final episode, which left it as the sole current affairs offering at 7pm until Story launched this week.
But while the programme is experiencing its best ratings to date, it is still hasn't matched the peaks of Close Up in the 25-54 demographic.
Perhaps the most concerning trend for broadcasters raised by the data is the continued decline of late news audiences on both networks.
The introduction of The Paul Henry Show to TV3 last year did give the network a boost, pushing it well ahead of Tonight in the 25-54 demographic. But the boost was temporary and by the end of 2014, both networks experienced their lowest late night ratings of the five-year period.
The launch of Newsworthy in June fell outside of our data set, but Nielsen figures show the programme drew an average audience of just 38,000 (25-54) in July - surpassing the previous low set by The Paul Henry Show in December of 46,000 (25-54).
But despite falling ratings, Jennings says there is still a future in late news: "I don't think those shows are in any danger."
Likewise, Gillespie says the network is committed to its late night offering.
"One News Tonight remains very important to TVNZ. In the year to June 2015, our share against 25-54-year-olds increased and our ratings remain reasonably stable."