When 'Tis Done

If a joke doesn't get a laugh during the first preview and then fails to get a laugh on the second preview, but then on the third preview gets an uproarious laugh, do you keep it?

Would you bench a player who hits a home run every third game and strikes out the rest of the time?

If you like the way something ends, the very final moment of the play, but nobody else (your director, your cast, your friends) seems to like it, do you keep it? If you have an ending that you don't like, but everyone else tells you its great...do you keep it?

Discuss.