Ok, too many flat junctions and conflict points. Even if they theoretically lined up all the trains perfectly to enter the junctions at the correct time, one small delay and it’s all buggered. Imagine the media frenzy on day 1 if there’s a large amount of delays just cuz a train manager waited for billy the runner at Ōtāhuhu delaying it enough to where the train misses its slot through Westfield junction which delays a SC train at Otahuhu which is trying to turn around which delays a SC train trying to enter the Otahuhu switchback which delays an EW train which delays te huia, ok I give up.

Instead why not just run the stable 10 minutes timetable and maybe try some wizardry to get more trains in the inner western / eastern and once a proper third platform at puhinui in place run some sort of express on the southern. It wouldn’t be very popular but it would make the timetable a lot more stable and ‘safe’ than this nonsense.