I have some questions on RMAN backup retentions and policies.

My requirements :
Regular day to day backup retentions : 30 days
Quarterly backups : 2 years
Year end backups : 7 years
All backups will be 'online' or 'hot'.

My Questions :
1) How do you (DBA's) typically manage deletion of backups (database, archivelogs, others) on a periodic basis? Do you let the backup tool (say Netbackup or Tivoli Data protection for example) take care of this by setting retentions there? Or do you setup RMAN scripts to do this? It appears that a lot of DBA's choose to do the latter..but I wonder why? Isn't it one less thing to do for the DBA, if s/he lets the backup tool/vendor take care of it? Yes, the recovery catalog will then be out of sync since it will indicate that certain backups (say 6 months ago) still exist, when it reality the tapes might very well have been reused after 30days by the backup tool/vendor. But then, can't you simply verify (or crosscheck), do a "delete expired" and resync the catalog instead?

2) How do you typically manage quarterly and year end backup retentions? Do you set separate "retention policies" (with keep / nokeep cluases) for these and then issue a "delete obsolete"? How do you ensure that the backup software vendor doesn't automatically reuse these quaterly/yearly tapes?

Thanks for your time. I greatly appreciate your inputs.
- Anand