We could influence short-term rates, but took a longer time to see this coming through on effective mortgage rates, because banks were able to restructure mortgages to fixed term and fund at lower international rates. Source: RBNZ. This is not to say that monetary policy was impotent through this period; merely that its effects were slower to eventuate.
This made it necessary to pre-signal to householders the pipeline impact. It also makes it harder to judge the timing of monetary policy moves around the business cycle with as much precision as we might like. Interestingly this is a problem that other central banks overseas are now also starting to worry about, though their economies are at an earlier stage in the cycle.