The problem with this intersection (and many others mapped in Auckland) are the slip roads.
The additional junction nodes created are adding a penalty to the navigation. Because the slip from Titirangi into Gt Nth does not align with the slip from Gt Nth into Rata and because of the likely average time spent in the sector with the traffic lights, Waze will see the slip roads as being massively faster by comparison.
I've noticed that many junctions around Auckland have had the slip roads mapped into Waze. Not only does it cause the sort of problems shown here, but many give incorrect TTS instructions (this one is OK as all the slips have been named with the road they lead into).
IMO slip roads as shown above are unnecessary; you get enough warning far enough out to realise that you have to move into either the left or right lane if you're turning. I would personally like to see them disappear as I don't think they add any value, but I'm still too much of a newbie to be starting this without further discussion amongst some of the older and more regular hands (eg. pcp, ispy, etc.)
And to answer David's questions:
1. You can turn into Pine from Great North Rd (including the right-hander, there is a lane for it - but it is restricted during rush hour): Fixed.
I've enabled the right turn into Pine, being that it's only a no-no for 2 hours per day and as a cul-de-sac I figure it should be OK.
You cannot turn right from Pine onto Gt Nth Rd: Fixed
2. A right-hander from Rimu into Rata is disallowed. This is correct.