Lem retains all data until the disk is nearly full then starts deleting the oldest records, so unless you need to maintain an archive that goes back farther than what you can fit on the disk (maxes at 2 TB) these backups aren't necessary for the purposes of looking at past data.
Now for good practices you should be regularly backing up and archiving the appliance (and by extension it's db) using the same methods that you use for all your other VM's.
I feel like those automatic daily backups of the LEM db are pretty much just a holdover from the days back before LEM became a virtualized appliance.
If you are already maxing out the 2 TB and still want to retain old records for longer then having these incremental backups is probably handy but I feel like that might be an edge case.