So, I've been thinking about running 100% and I'm currently routing it out and it would be a big help for me to know if buying the extra heart is necessary as it is a recurring item and is not a one time purchase

Yes, buying the heart would be part of the 100%

thnx this will help with my routing and when I finish my route do you want it on the guides section for the game

That would be great! It'll help future players

its helping me too the biggest challenge is routing out when to buy items in the shop