We do not have such guidelines. Veeam database contains only configuration tables for your backup jobs and not the actual backup files, so almost nothing to optimize.
I think that I've seen some tech notes from Veritas on that topic too. Currently the only form of maintenance that is available is configuration backup
. In v9 there will be a maintenance job to cover the reorganization/rebuild of the indexes on tables, database statistics updates, and a few more things.