Documentation of RPZ min-update-interval is inconsistent with implementation
The ARM states:
Updates to RPZ zones are processed asynchronously; if there is more than one update pending they are bundled together. If an update to a RPZ zone (for example, via IXFR) happens less than min-update-interval seconds after the most recent update, then the changes will not be carried out until this interval has elapsed. The default is 5 seconds.
But the actual default seems to be 60 seconds: #define DNS_RPZ_MINUPDATEINT_DEF 60