I always used printed music..till one day in the early 90's I had a job with a young lady, about an hour away...I forgot the music books...

I started out playing the more familiar tunes, and low and behold...I realized I already knew the tunes...Here I am 15 years later, and never haul sheet music to a job..

I even to this day can play tunes I played 40 years ago via sheet music...without sheets, and in original keys...I one time I always thought I had a photogenic mind when it came to sheet music....I could picture the songs in a fake book, right down to the page number[serious]..

Now lyrics are another story, I can remember many tunes, how be it, swapping around verses and words...but you know what? I have heard my music buddies do the same ..

I also believe a strong vocalist that backs them-self, can get by without sheet music more easily...just 2-5 ing there way thru a tune....