97 verse ballads.
In my experience a ballad performed at a folk club can have anything from 2 to around 20 verses on average. Though there are ballads and songs in print that exceed this number, I have never heard them performed

Before I read Don's posts, I was reminded of Ian Maxwell, whom I first met in the early 60s. At that time he lectured in English at Melbourne Uni and his lectures on poetry to first year students (about 350 all told) were given in the "Public Lecture Theatre" with a seating capacity of 850. Routinely there was standing room only, with students (and staff) from other years, other units, other courses and other faculties crowding to hear him and routinely they'd have tears running down their cheeks at the power of the poetry and his presentation.

Honours students in English were, at that time, required to do a separate set of studies after first year and these studies, many convened by Ian Maxwell, included Old Norse and Old Icelandic; I still remember him referring to Pharoese as "Old Norse with a North Fitzroy accent" (North Fitzroy was at that time a very working class suburb in Melbourne. I also recall him describing some of the Old Icelandic ballads as requiring not only singing, but dancing as well, and that some of them would go on for three days and nights.

In our enthusiasm for writing, and reading written records, most of us have lost (or never even learned) the techniques of memorising lengthy passages. The last autodidact I knew was the blacksmith who worked (in retirement from doing it for all of his working life) at Sovereign Hill, a museum of mining operations set in a reconstruction of Ballarat (Victoria) set in the 19th century. Like many autodidacts, he could recite the whole of Paradise Lost and many of Shakespeare's plays.

Puts "97 verse ballads" a bit in the shade. And says a lot about attention span, too.

Don's points are, to me, well made; the only recommendation I'd add would be to check out Robert Fagles' translations of the Iliad and Odyssey; not only do they engage poetically (rather than just as literature translated prosaically) but the introductions deal extensively with the timing of the works as oral tradition recorded and collated at the onset of writing.

When GUEST,bill S from Perth wrote
One of Australia's leading trad Australian bush singers admitted that he knew most of the Robin Hood ballads but couldn't sing them because it was not what was expected of him
he could also be describing, with some accuracy, Hugh McEwan. When he first arrived in Melbourne Huge (as he became affectionately known) was routinely asked to sing his collection of Robin Hood ballads; one needed a Scots dictionary but they were all the better received for that.

More than 20 lines; I hope the attention span isn't too strained.

Cheers, Rowan