They would have probably been allocated by GMH, not ordered by GMHNZ. GMHNZ probably had input into how many they thought they could shift, but the final production scheduling would have been by GMH head office.
Remember CKD was two packages, a mechanical pack and a body pack. The body package came from Woodville and the mechanical pack from Fisherman’s bend. Thus they’d be put together as required and as parts came together.
Remember also how many went across to NZ at once would be governed by the Logistics group of GMH, a shipment of CKD and SUP plus whatever else was going over (eg consumables like paint) would be planned in advance and this would dictate the schedule for production.

I'm pretty sure you'll find the decision what to make and market would be GMH with heavy input from NZ. It would all be driven by what they thought would sell, and probably the small market and the tyranny of distance meant they could sneak higher spec into the stock vehicle and thus make more money per car - probably both GMHNZ and GMH were party to this. My answer was about the notion of batches though, the CKD packs are not related to vehicles over here thus if there were say 50 made, they are most likely 50 consecutive CKD packs for NZ and thus are a batch by nature regardless of whether the original decision was made to build 50 or sales later dictated that was the number. My guess is though that GMH made the final decision regarding how many they would build as SUP or CKD as they had to fit all of this into their own production and logistics schedule. This decision may well have been made right at the start of the series too.
All of it would have been important though in the scheme of profits and they would have had to have a business case for each series, and exports would factor into it, just like the exported Commodore, Monaro and Statesman numbers were important in the business case for those. I was actually reading yesterday about Fiat Australia's push for the 2019 Ram1500 to be produced factory RHD rather than be an expensive conversion like the Ram2500 and 3500 that Walkinshaw are doing, the business case being the small but significant volumes Australian and South African sales would bring would raise the Ram above Chevrolet Silverado sales and closer to Ford's F trucks and make each vehicle built overall cheaper per unit. Hopefully the push goes ahead as it would mean a Ram1500 (that Walkinshaw converted would cost us here in Australia around $120,000 (similar to Tundra)), would be around $60-$70k Aus. These are not significantly bigger than a Ranger but can safely tow 3500kg and have engines from a small V6 diesel up to the SRT's 5.7L Hemi V8. The comparison being similar for GMH back in the 70's I guess, NZ was a small market but the extra few 1000 cars overall made each series more profitable. With a Ram if it happens, and like described for the Holden I bet we get limited choices here too as the small market means they can squeeze in mandatory options and ask a premium for it.