To pick up the point Gargoyle raised. The 24 hour default for the time filter on the Mudcat can be a bit of a nuisance, especially when the Mudcat goes down for a bit. I don't think grading threads for quality and a time extension would work though.

Easier thing would be to adjust the filter manually, if you've been away a bit, and then add a post to the more interesting threads that have slipped away, so as to refresh them.
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I'd imagine that most times what happens would be, a script writer would pluck a key out of the air pretty arbitrarily, and the actors would say it, and the actual music would be recorded seperately, and subsequently. And I can't see it going down too well if someone at a late stage said "You'll have to go back and shoot that scene again, because she said D instead of G".