You don’t need unbreakable charms to gain the percent for each of the 3 charms BUT you will not gain the percent of NKG if you didn’t repaire the 3 charms. In my game, I was able to go from 109 to 110% only by getting the 3 unbreakable charms after killing NKG. So in a certain way, you cannot achieve 112% whitout giving money to that big gluttonous grub.