I think that there are a few other things that the reasons that the older & longer ballads were not just repeat verses boring themselves into a yawn. And I do agree with Don to a certain & again wit Jack. We all know the todays attention span is nil compared to when people entained themselves bu fireside & candle light. They also sang to their peers, both younger & older as ways of communication not just as entertainment. Lessons were told, say of subjects like courting, payback, sibling behaviors, marriage, life in a communal setting, etc. These lessons took repeating in not only the same songs but the same lesson could be learnt in a different fashion & cover the same topic but overlap an ajcent lesson area by singing a different song. It was a past time enjoyed by elders watching youth develop & feeling the joy & respect of knowing that a good lesson was being passed on & of the lesson being learned well. There's also the pride of hearing a mid aged singer knowing that an elder, possibly their mento is listening & hearing an old lesson getting pasted on by a former fleagling to a youth who's just hearing their fir the first time that it's not just a song getting past on but also a life's lesson. In some cultures one a song gets passed on from a mother to a daughter or father to a son, the elder will no longer sing that song, where before hand the younger singer wouldn't sing the same song without the elder's permission.
Also in the older & longer ballads there's a sort of trace building when sung within one's own community. The futher one looks, under the stone , behind the cupboard, below the floorboards not only the suspence build up but it's job was to draw in the listener who know ofthe same stone, cupboard & floorboards.

Todays society doesn't require the same from it's singer as it did long ago but it still requires the story at least if not the basics
of some of the lessons. Most of us don't need to know the whys & whats aboyt farming hunting, fishing, courting & all. Even when if we did we now learn them from otjer sources outside of our communities. So the singing of the longer & more complete texts of the ballads is a choice & a line for the singer to draw. The singer also needs to be aware of it's crowd too & where they'd like to draw the line. To long & you're lost your crowds ear, too short & you've cut the ear off prematurely.
I also think it's an important responsiblity for the singer to first know as much of & about the ballad as possible so the making of the song as one's own to sing is as possible as can be. The same would be true of making one's self as familiar with one songs versions, varients, cousins & offsprings as warranted. Of course this vcan only go so far & only be expected within reason. Thought the futher one goes with this the greater the grasp on the song, it's story, it's meaning, it's lesson & it's joy in singing & hearing. Voice also counts for something here too, as does presentation.
So what's been whittled & culled or added & replaced to should be given a decent amount of care & thought.

Barry