there are good reasons to fix (tho you've missed the boat to some extent by now)
I value knowing that my mortgage is (largely) fixed for 5 years as it allows certainty in budgeting and planning. Less importantly it costs less too as there is a admin fee each time you roll over.
But I also knew when I fixed it at 6.5 in April that this was historically a very low number. last time (in 2003) when I fixed at a similar level I never regretted it
Its seems to me that in NZ with our high interest rate premiums due to being a small indebted nation they will never go particularly low esp when you know the bank wants 3.5 and the country's premium is what ? 2 at least... so there is no chance in hell of them ever going below 5 , so to lock in for 5 at years at 6.5 seemed a sure thing as it gives me certaintly with no huge premium for that. dont think I would be fixing for 5 right now tho.