If the average person’s efficiency is 75%, then say “Heroic Feat with Luck” is a maximum of 125%
Mostly, you can exceed 100% efficiency, but as a spring - the stronger you need to compress, the more energy you need
100% energy = 100% result
150% energy = 110% result
215% energy = 120% result
300% energy = 125% maximum result
possibly skill + skill = penalty WP/AP or skill + skill = skill + 50% of skill