RMAN backup optimization

  Hi

we have configured RMAN backup with backup optimization on
The database is a TEST database for testing RMAN backups and recovery and does not get changed at all
we run the database backup everynight

here is the script

configure channel device type disk clear;
configure channel device type sbt clear;
configure retention policy to recovery window of 1 days;
configure controlfile autobackup on;
configure device type disk backup type to backupset;
configure channel 1 device type disk format 'd:\rmanbkp\%U' maxpiecesize 2048 M;
configure controlfile autobackup format for device type disk to 'd:\rmanbkp\cfspf_%F';
configure backup optimization on;
run {