Depends whom I'm playing with. With some guys, who can take a bit more improvisation, I prefer not to use the hard copy. You definitely play better when it's in your head and heart alone.

But when I play with others, (like our 5 piece band, Blarney), I use one, more as a road map than anything, since none of the stuff is that difficult to play by ear. But these guys are pretty stuck on hard arrangements and get flustered if you don't stick to the plan...

"Okay, we open with a fiddle intro as the last two lines of the chorus, then sing verse, verse chorus, verse, vhorus, fiddle break as a verse, sing another chorus, last verse and chorus, a capella chorus, then one more chorus and the fiddle takes us out with 4 more bars..."

Same thing every goddamn time. You'd think I could set it on autopilot and go, except we don't play that much and the leader likes to change the sets around a lot.