Big numbers of special votes and enrolments took a toll on vote counters in last year's election.
A report on the count by the Auditor-General has found the final check of the official result was done in a few hours, on the day it was announced.
The rushed assessment failed to identify multiple errors.
It normally takes two days.
Chief Electoral Officer Karl Le Quesne says they're working at ways to better support staff in future.
"We need to look at how we can use technology to identify potential errors - there might be some more staff needed. But we need check more robustly that the checks have been carried out as well."
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