In most cases, the overall power of an attack or spell did not depend on the amount of energy used. That was important, but much more important was how the energy was used and its density.
Thus, there was a significant difference between a master in the use of lightning skills and a beginner who was just starting out. Even when they reached roughly the same level of density and amount of energy, the master would always be much stronger because of his skill.
This rule worked for absolutely everyone, including Liang, The Strongest One. He had unique abilities that others didn't have, but he was also one of the best swordsmen in the entire universe.
When using his skills or wind power, he did so naturally, but because he had several hundred years of experience.
Only when he reached the pinnacle and discovered the mysterious power, only then did he stop devoting weeks or even months to practicing.