Stuck on Main Quest Stage 55

To buy items from the Heart Shop, you need to save up a lot of hearts. Even though I open the 200-heart treasure chest three times a day, I can barely save any hearts... How does everyone save so many hearts? Did you guys stop opening the heart treasure chests when you were on Main Quest Stage 55? Honestly, I feel like the items in the Heart Shop aren't very cost-effective. The 200-heart treasure chest is the most cost-effective. I'm curious about what items everyone buys from the Heart Shop. Thanks, everyone.