I was at the first performance of this, the day after the event it commemorated:

Steve Byrne's song on Nigel Farage's visit to Edinburgh

and Steve used a sheet when singing it. I would too.

Contrariwise I have been encountering a specific problem with slow sessions where people use sheet music. They often use books (like Nigel Gatherer's) with three or four tunes to a two-page spread. And usually those tunes do not belong together. But the peple who use the books regard the typographical medley in front of them as an unshakeable musical reality. The result is you get idiocies like two marches followed by a waltz, or (my pet hate) sets that randomly switch between tunes that fit in the pipe scale and ones that don't, which buggers up instrument selection for multi-instrumentalists and shuts smallpipers out entirely. Do these people select their friends from names occurring on the same page in the phone book?