Say there's a thread about a show but new info has arrised, would making a post about it be ok but then it could be locked?
All information should be maintained in the therad most appropriate. Say there is discussion about the show in NYC... if you get more information about what Vanessa will be playing or wearing -- that goes in the existing topic... no need to start a new one.
If you have a new topic like... "Meet up in NYC for June 3rd concert!"... that should go in a different thread because the existing thread is for the show, not the meet up.
If people want new info for the show, they'll read the thread. If the thread goes off topic in the middle, it will be split and only pertinent info left in the thread.
Never, at any time should the goal be to start a new topic but have it locked shortly after... locking is when something is done wrong...
Here is a good example:
http://forums.nessaholics.com/viewtopic.php?p=5085#5085 ... this was done absolutely correctly and the Mods <3 this