My first answer would be "NEVER!". But then I read comments posted by other members who might know the judging process better than me, so I changed my answer for "Almost NEVER".
I don't think that judges should be able to have a look-see at programs. Because, and recent years' events would tend to prove me right, they are way to fallible: It remains to be proven that a judge would not give marks for a fantastic practice session. Or for a so-so program by a top-ranked skater.
That thread made me think of another phenomena that irks me to no end: the "Your Time Will ComeTM" theory. The theory that made that Bourne and Kraatz won their friggin' very last Worlds.
I remember reading a comment made by Sophie Moniotte after the Salt Lake City debacle. She said something to the effect that a skater or team shouldn't worry if judges are unfair, because someday, their time will come to win. Right, Sophie.
So by that rationale, Timothy Goebel might win the Worlds in... 2007. Or earlier if Plush and Yags retire before Turin. And if the Elvis school of skating is fashionable again and Takeshi Honda becomes the judges' darling. Oh, whatever.