What is the duration of courses in New Zealand, and how does it affect post-study work visa eligibility?

Master’s courses in New Zealand are usually 2 years in duration, while a few are 1 to 1.5 years as well. If the Master’s programs is Level 9 program, irrespective of it's duration, it makes students eligible for the full 3-year post-study work visa if studied full-time at an approved institution.