With the adaptive scheduler disabled (the default), every planning pass
on the main poll tick rebuilt each instance task with NextRun=now and
Upsert overwrote the pending slot, so availability targets polled at
the tick cadence regardless of their configured interval. Reproduced
at exactly 10s polling on a 60s ICMP target; c70431caa only covered
the adaptive-scheduler path. Planning now preserves a pending future
slot, tightening it only when a freshly shortened interval justifies
an earlier run.
Refs #1745
rcourtman
8d9d567f62