You can use Vault to duplicate backup images daily and eject volumes weekly. Duplication occurs every day rather than one day only, spreading the workload evenly throughout the week. The media remains in the robot until it is due to be collected by the vault vendor.
For example, if the vault vendor picks up the media every Friday, you can do the following:
Configure a second Vault profile to do the catalog backup and eject steps. This profile should use the same image selection criteria as the profile that duplicates images. Configure a Vault policy to run this profile before the vault vendor arrives on Friday.