Like Vic, I sometimes sign when someone announces they'll be reciting a long poem. I've sat through many poems that drag on, giving you a good opportunity to call to mind your shopping list or plans for the weekend.
However, like Marty, I don't mind if it's well-presented and a great poem. It would be a poor world that banned The Man From Snowy River because it is too long. Zondrae posted recently about a fabulous rendition of TMFSR at a poets breakfast at Kangaroo Valley, and if I remember correctly we got through everyone who was on the list that morning. (We were lucky!)
IMO performers should always take the situation into account before they select a poem to perform, and that includes time constraints as well as type of audience.
Perhaps the trouble is most performers think their version is better than average
Robyn
Robyn Sykes, the Binalong Bard.