Hello! Skill Breakthrough using Skill Trial is based on chance and not guaranteed. This means that there is always a chance that you will not get the "golden" breakthrough which is the maximum breakthrough for its respective skill. There is no set amount of resource you require to breakthrough using Skill Trial, as it is based on chance.

Skill breakthrough has two tabs: Skill Trial and Skill Breakthrough. The second tab, "Skill Breakthrough", allows you to guarantee a skill breakthrough by using Skill Books or respective ninja fragments to craft the necessary Skill Book for Skill Breakthrough.

Hope that helps.