From: Jim Carroll - PM
Date: 06 Jul 17 - 06:33 AM

At the time singers were capable and happy to let forth with twenty verse ballads - word perfect from memory

"Twenty verses - word perfect"
How could anyone tell, if no-one had song-sheets to check?
They might be the same 20 verses he sang last week, or they may have changed, but people were unlikely to recognise the fact.
Similarly they might not be the same twenty verses that others sang for the same song.

Without some standard of reference you will never know whether he was 'word perfect'.