Other students who were involved in arts, dance and drama were struggling to balance it with their six-weekly internal assessments, she said.
Lloyd-Parker said she wanted students "to feel that they were actually part of the world".
She had "a hell of a lot of faith" in the Cambridge system, and said it was "really, really clear".
"Girls know where they're going and they know how to get there, not if they're brilliant, but if they work really hard, and so for me, from what I saw, it was a perfect system."
She liked that she could also tailor the programme to suit individual students.
Lloyd-Parker said her school is not the first in New Zealand to scrap NCEA, but that it is the first in Wellington to drop all three levels of the system.
"We're in the capital. Wellington's a wonderful, wonderful city. I would like to think in the capital that we weren't afraid to take a step forward in education and see what happens, so we have.
"I guess the proof will be in how well the girls do, but I'm pretty confident that they will do really, really well."