Wow, 2012 huh? Man time flies.
Yeah to get hearts playing on higher intensities helps. What do you need the hearts for? If you're trying to buy a weapon I recommend not wasting the hearts as you can just play on higher intensities and fuse weapons to get something of that calibur. If you're trying to get something from a gem though...good luck. Some of those are crazy expensive. Might take you a while to get those.
How far are you in the game anyway?