Public speaking is good comparison. I never work from a script when giving lectures or addressing a conference etc, as, just like everyone else, I don't write as I speak. I am like many people in that I may never look at my notes but if they weren't there, I'd probably do a Miliband. Notes are bullet points of what I need to get across. Bad enough that students don't see my bit as a core subject and conferences, I am usually the warm up for those they have really come to hear and challenge.

Same with the piece of paper stuck to my guitar. It may have the first line of verses, or a few words I tend to get wrong, but rarely the whole song.

But..

Yes, I have been known to use lyrics, even my iPad before now, in a sing around. Not easy as for other reasons, I have problems sitting and playing, I tend to stand.

I think we are somehow confusing singing with performing. As a listener at a concert, you have expectations of the performer, including body language, ease of delivery and a good performer makes you feel they are addressing you, not a crib sheet. When I was in rock bands, yeah, the running order, keys, which effects pedal etc may have been taped to the floor or on my foldback speaker.

This thread has the words "on stage" in the title. it therefore isn't an excuse for another thread concerning mumbling into a book at a sing around?