If there were no changes on the tenant, we do not create a new snapshot. This is because the previously created snapshot will reflect the current state of your tenant.
Each time we run a backup job, we check to see what changes were made on the tenant and back up all new and modified items, and remove items that are no longer on the tenant. We then create a new snapshot, which includes these changes. For data that was unchanged, the snapshot will also contain reference points to previously backed up data. However, if all data was unchanged, then we will not create a new snapshot.