I worked with a chick singer who could not function without her book of lyrics and music stand. Had to turn back 30 miles down the road to a gig because she forgot the book. The book was the only thing she ever carried in or out at a gig. She'd been singing Moondance (Two verses!) for 20+ years and couldn't do it without the book. Her bassplayer husband wrote out the lyrics for her, so he knew them all. Writing down the lyrics in longhand seems to imprint them in memory, it's how I did it anyway.