The issue with David missing some lines goes back to how viciously and unceremoniously Simon and other judges cut ANYONE who forgot a single lyric during the Hollywood auditions. There was no acceptable excuse at that point in the competition.

Certainly there isn't now. David simply didn't do his homework. I don't know if it was a time element because of the photo shoots, or whether he simply got over-confident, but even if he doesn't go home, that mistake MAY have cost him the "title". It sure dampened my enthusiasm for him.