The Log Copy Queue is only used for Transaction Log Backup jobs.
When you perform a Full or Diff backup using the COPYTO keyword, the copy process is perfromed within the backup job and as a retry count as set by the DISKRETRYINTERVAL and DISKRETRYCOUNT keywords, by default is upto and including 10 attempts every 30 seconds. To check the success of the copying process you need to view the SQL Backup log file for that job. In the SQL Backup GUI ->Activity History tab may have a warning triangle to indicate that the backup was successful with warnings.
To help with a Log Shipping setups, Transaction Log Backups using the COPYTO keyword, the copying process differs. The copying process is perfromed outside of the log backup job. When the Log backup completes successfully, the job ends and an entry is placed into the Log Copy Queue. The SQL Backup Agent Service checks the Log Copy Queue and attempts to copy the log backup file to the configured network share. The retry attempts will take place for a 24 hour period. This SQL Backup help article
contains further information.
I hope this answers your question.