BlinkyBill:Mate, I am not confused. If you were employed for over 12 months, add up the total number of hours you were paid for and divide by 52. It is not relevant whatsoever if you worked 5 here and 25 there.
You may well be correct however I wouldn't be so confident until you can point to specific official advice. As above I think those citations are relevant and contrary to your interpretation. When Hon Grant Robertson says "use normal hours in the period before COVID-19" I don't take "before" to mean an entire 12 months.
The scheme has already been significantly updated at least twice due to oversights, Ministers have had to produce numerous individual clarifications as well as the constant website updates. I don't think this is as clear cut as you think and there's no reason to think this isn't another grey area they need to tidy up.
In fact "ordinary wages" and associated terms have specific meanings and calculations in both the Employment Relations Act and Holidays Act (which is also referred to by other Acts not just related to holiday pay).
For example:
http://legislation.govt.nz/act/public/2003/0129/latest/whole.html#DLM236852
8. Meaning of ordinary weekly pay
(1) In this Act, unless the context otherwise requires, ordinary weekly pay, for the purposes of calculating annual holiday pay,—
(a) means the amount of pay that the employee receives under his or her employment agreement for an ordinary working week; and
(2) If it is not possible to determine an employee’s ordinary weekly pay under subsection (1), the pay must be calculated in accordance with the following formula: a − b / c
where—
a is the employee’s gross earnings for—
(i) the 4 calendar weeks before the end of the pay period immediately before the calculation is made; or
(ii) if the employee’s normal pay period is longer than 4 weeks, that pay period immediately before the calculation is made
b is the total amount of payments described in subsection (1)(c)(i) to (iii)
c is 4.
There are similar calculations for "relevant daily pay", "Average daily pay" etc.
There's no reason to believe that "ordinary wages" would not be intended to be treated similarly to "ordinary weekly pay" based off the greater of the last pay period or 4 week period; which would make a lot more sense than "your average over the last year" (which I can't find used anywhere else apart from the subsidy level eligibility).