Frodo was lucky enough to be on a quest for a location. A mapped location. That makes it easier.
Harriet, of course, had it easier than Harry. Harriet was looking for a prince. That is to say, looking for castles. Even if the prince is not there, someone may know where he is. Assuming they're polite, of course.
Harry was searching for something he didn't know where it was. It's kinda hard. Floundering around without a clue doesn't form a plot, but larding in the clues takes a deft hand.
I wish my muse didn't like them so much.