If it is an actual Burns Supper then of course only one person would be reciting "To A Haggis" as that is recited when the haggis is brought in. Though I took it the OP is asking about songs rather than reciting long poems. In my honest experience unless folks are actual poetry buffs then even when things like "To A Haggis" or "Tam O Shanter" are done really well by people who know them inside out the eyes of many folks glaze over by the time the first few verses have been done. It would be torture even for buffs though to sit through someone trying to get through it if the performer didn't know and perform them really well. I think the songs are a much better way to hold the audience as they are easily learned.