I set preferences for 3 backup folders inside the DT Pro database package.
The Backup & Optimize (or auto-backup) operations automatically replace the contents of each folder in this order:
Backup holds the contents of the most recent backup;
Backup0 holds the contents of the previous Backup folder; and
Backup1 holds the contents of the previous Backup0 folder (previous contents of Backup1 are automatically deleted).
Note that Tools > Restore Backup is a reversible operation. If you select Backup, your current database will be swapped with the contents of the Backup folder. If you run Restore Backup again, once more choosing the Backup folder, you will be back where you started. This allows you to choose among the available backups to select the most recent ‘good’ one for your purposes.
I really don’t encourage deleting the backup folders inside the database package. Things can go wrong – your could have a power outage, a System crash, etc. that could corrupt a database. Three backup folders is “safe” overkill; I like that safety margin. Ten backup folders I would consider to be “excessively safe” overkill.
I very strongly encourage external backups, preferably on external media, in case of a loss of a hard drive. DT Pro provides a script that can make the smallest possible archive file of your database. Choose Scripts (“S” symbol) > Export > Backup Archive.