Trick over-estimates me.
I guess I've watched too many zombie movies, shows or read zombie-related fiction (or is it non-fiction? Hmm). But a common denominator is "Get walls between the zombies and the survivors."
Panic room
House
Mall
City with walls around it
Heck in Max Brook's "World War Z", the Rocky Mountains are used as a "wall" to separate the survivors on the west side from the zombie horde on the east.
Any situation like the one on the farm where a group of survivors needs to post a look-out because they do not have the security of walls... Well that's going to wear on them.