I'm playing through Hero Mode. After I started the Lanayru Mining Facility, I left, got one of the Heart Medals, and returned for the rest of the dungeon.
I destroyed three or four dozen barrels and pots after equipping the Heart Medal, and in that whole time, I got only two hearts, plus one each from two Spumes, for a total of four.
I didn't even get hearts from the pots that were previously guaranteed to have hearts. I didn't even get hearts from the pots in the boss chamber!
If a Heart Medal gets me only four hearts per dungeon, I think I'd rather leave it with Peatrice and carry something else. Is this typical? And when I get the other Heart Medal later on, will carrying both render them any more effective than carrying the one?