There is nothing worse than losing data in your accounting package. Data corruptions can happen at any time, which is why I recommend in Sage50c saying yes to checking your data and backing up at least once per day ...
This also means you should check and backup before you do a data import or anything else which could change your data. These backups are there so if your data is ever corrupted (which can happen for many different reasons) you can go back to a 'clean' non-corrupted version, though you may need to re-enter any new data since you took the backup.
But what if you have been using Sage50c for years, and you are backing up your data every day, you may well have a huge volume of data backups filling up your disk space so what should you do?
When I reach the end of a VAT quarter or the year-end, I take an extra backup and just add a comment at the end of the backup file just before the,001 to say VAT or YEAR-END so these backups stand out in the long list of files.
Then once a year, or more often if disk space is an issue, I go back and delete all the normal 'daily' backups from the past, as it is unlikely these will ever be needed, but just keep the special backups marked VAT or YEAR-END.
It's just another maintenance task that you should undertake regularly so you don't end up with a disk full of needless data. So, when did you last tidy up your backup folder?
If anything I've written here resonates with you, call me on 01604 420057 and let's see how we can help you.