Today’s Question: Is it necessary to keep all your Lightroom Classic CC backup folders, or just the last five to ten backups?
Tim’s Quick Answer: No, there isn’t a significant reason to retain a large number of backups for your Lightroom Classic CC catalog. I generally recommend retaining several of your most recent backups, as well as one or two backups that are perhaps up to six months old.
More Detail: First, it is very important to note that when you use the backup feature in Lightroom Classic CC, you are only backing up the catalog, not the source photos being managed by Lightroom. So you’ll still need to perform a backup for your photos in addition to the catalog backup.
The catalog backup essentially represents a copy of the actual primary catalog file. If your catalog ever became corrupted, you could replace your corrupted catalog with the most recent backup, and you will have only potentially lost information that was added to the catalog since the time of the most recent backup.
In theory, to recover from a corrupted catalog you only need a single backup. However, it is possible that the backup would still retain some sort of problem that could make that catalog unusable. This is highly unlikely, but out of an abundance of caution I recommend retaining more than one copy of your catalog backup.
Therefore, I recommend retaining your most recent catalog backup, as well as two or three other relatively recent backups. Which you retain will depend in part on how often you update your catalog and how often you backup your catalog.
As an additional precautionary measure, I also recommend retaining a backup that is a bit older. The idea is that if there were some sort of recent issue that caused corruption to your catalog, an older backup would hopefully provide an option for recovery without that corruption.
Of course, restoring from an out-of-date catalog creates a new set of problems, which is part of the reason I also highly recommend enabling the “Automatically write changes into XMP” checkbox on the Metadata tab of the Catalog Settings dialog.