I had the impression that the Warners recorded only a few verses of a song and Ann Warner took down the rest in shorthand.
The Flanders Ballad Collection, on the other hand, has recordings of entire songs. Everything the singer could remember. I have listened to some of the Flanders Collection reel-to-reel tapes at the Library of Congress and must say that I prefer hearing the whole song, the whole story from start to finish.
Hopefully, one day, all of our great field collections will be available to the public on CD. There is nothing like learning a ballad from the person who loved it and made a point of wanting to pass it all to others.