Instead of locking a topic, when you're satisfied with what you have received it's better all round to get a Moderator to put *COMPLETED* on it (by sending a Report To Moderator). That way people who've already started still get a chance to add their work to it, but new restorers will be able to see that they don't need to contribute and can move on to another one.
Our guidelines (topic at top of board) give a general guide of 48 hours before marking a topic "completed" - this gives everyone a fighting chance of contributing. However, even if a thread is marked "completed", it shouldn't be locked, for reasons given above.
Hope that clears things up for B/B and others
