Not only is the event fluid, but TM Preview night itself is literally one of the main times to test these things to find places for adjustment.
Very little value should be put into TM Preview night realistically. Reactions are going to skew positive (HHN 29's preview had people commenting on here that Ghostbusters could be HOTY and then most people felt very underwhelmed towards it), things won't be fully fleshed out yet, experiences won't be completely normal, crowd levels are dramatically different, etc. Take the preview as a time to discover some spoilers, maybe help adjust your gameplan, and not much else IMO.