It does depend on the amount of transactions that are happening within the tables / applications.

I would suggest that the T-LOGs are backed up every hour or even every 2 hours. the full backup should be done once a day.

But all of this does depend on your disaster recovery plan and system availability. A 58gb database is not large in SQL terms - but is the data ALL required ? - could you archive any old data and therefore reduce the size of the database ?

Do you do any other maintenance ? Truncate tables / shrink tables/databases ? to return free space back to the system ?