You say "The data from the log could be unavailable because the data has been overwritten in the log. This could happen on databases that use the Full recovery model when a full backup is done. It could also be that the database is using the simple recovery model. In the latter case, there is no guarantee that the data will be available."
Surely, having Full Recovery is a normal case and taking Full backups is a normal case.
We take backups once a day and backup the logs every two hours, why would data be unavailable for many logs in the day?