are there any possibility to use Oracle flsh recovery to undo some user mistakes?
Correct me if I'm wrong, but I think you are confusing the Fast Recovery Area with Flashback.
The Flashback feature is only available in the Oracle enterprise edition.
Flashback stores its logs in the Fast Recovery Area; you can only use Flashback if you enabled the Fast Recovery Area.
Note: Starting from Oracle 11gR2, the Flash Recovery Area is renamed to Fast Recovery Area
or should I use media recovery every time?
It is up to you whether Flashback or media recovery (I.e., Backup Exec restores) should be used.
If you are worried that using Flashback may adversely affect Backup Exec's backup and restore operations, it doesn't.
In general, use Flashback if the data you want is still in Flashback.
If the data is out of Flashback's retention, then use media recovery (Backup Exec).
Like all other CDP or CDP like solutions, Flashback generally only goes back a few days/weeks.
For longer term backups (months/years), you recover from media managers like Backup Exec where data is stored in long term storage media like tapes, slow disks, etc.
Flashback allows you to do very quick and granular restores that Backup Exec cannot do, such as restoring a single record.
But again, it is about short term vs long term storage, quick vs slow restores, granular recovery vs complete db recovery.
