Here’s a quick pointer towards the Tararua Fastest-Known-Times site , which has been spread around social media in the last few days. It caters to a mentality which doesn’t so much appeal to me, but which has a good following. My own preferred form of back-country turture would be one of pushing through leatherwood at 100 metres an hour. 🙂
There’s at least a loose history of running in the Tararuas, going back at least as far as the likes of Sam “Big Mac” McIntosh, Bill Gibbs and friends in the 1940s, as documented by Chris Maclean’s Tararua history. More recently there are certain people around who have always looking at challenges like running an SK, or a Southern Main Range loop as a day-trip, or otherwise. It’s grown in the range as a sport in the past few years, however, with the influence of local running groups and relatively recent events like the Tararua Mountain Race  and the Jumbo Holdsworth Race , as well as a growing community in nearby centres.
The increased interest naturally comes with new challenges, particularly where safety and skills are concerned , but hopefully the protocols around what’s acceptable in a new activity will become well established over time. And yes, I know there are plenty of people out there who already think carefully about this.
On the off-chance that you enjoy this type of thing, you might also like Taranaki Speed Records , which documents the speed records for such enlightening achievements as the most times ascending (and descending) Mount Taranaki in a 24 hour period.