Thanks for the reply. 20 minutes sounds reasonable. The reason I mentioned 5% was that it was the only percentage referenced in the NZ AIP's. But 3% would indeed be better. Where I work, we also have the 20-minute reserve. We use it when statistics don't yet support CONT 90, 95 or 99. For example after exiting COVID most routes went from CONT XX to 3%, 5% or 20 mins. for a while, before going back to statistical.
There is only mention of re-dispatching and 5% in NZ AIP though I suspect, their Ops Specs have more options.
Thanks again for the reply ...