Why is Ann glad that she didnt run straight to the cave ?

Ann is glad that she didn't go straight to the cave because Faro tracked her movements, which would allow Loomis to know exactly where she'd gone. Faro follwed her scent down the road first, which would lead Loomis to believe she's gone in the other direction. He wouldn't be able to see Faro's movements, and for a time she would be safe.