It is obvious from the above that most regular singers feel that it is best to KNOW the song....but there are times when it is a problem.

One example: In my club, we have a monthly "Open Sing" with a topic announced. It is often a spur to learing new songs and dredging up old ones....but often, the perfect song for the topic might not be 'locked' in the memory, even though you 'almost' know it. Then a cheat-sheet...just to remind one of the verse order, etc. can be a blessing.

My rule is: ***If I can close my eyes and not be able to tell that a person is reading some of it, I don't worry***....but if they barely know the tune, and have only printed off the song that afternoon, and are unsure of the pacing and have to stop and adjust their glasses and turn pages, it is no fun for anyone!

Certainly, folks giving a concert, and who are expected to KNOW the songs, should only in special cases use notes. I have seen some wonderful professionals read from notes because they had something new which needed to BE in the concert....but that is rare.