One of the user has been confused to see lot of .TUF file within their server where the log shipping is enabled. Basically this .tuf file is the T ransaction U ndo F ile, which is created when performing log shipping to a server in Standby mode. So if you ask why standby mode, database recovery is done...
Say which is better, having multiple transaction log backups files or single transaction log backup file during a recovery point of time. In my experience both of them doesn't make any difference and if you are performing further backup to tape then ensure to test them by restoring on to the standby...