ARCHIVELOG DELETION POLICY for a physical stabdby db: Shall I configure it on primary or standby?

We run a RAC database with a physical standby db. The backups are taken on the primary site. We want the shipped archivelogs to be deleted automatically on the standby site after its application to the standby db. For this reason we said CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON STANDBY in RMAN for the standby db. So far this worked well for some months. Now we realized that we should take at least 2 copies of backups of the archivelogs on the primary db. To this end I looked at the RMAN manual again and found the clause BACKED