Bruce Lee had a date with destiny to develope more and more power.
Be it internal or external he was looking and working hard on developing power.
The only problem to this classical mess as Bruce lee would put is, no one was willing to teach their students.
So if you were to measure striking power this hung teacher after 5 years of his training and measure 5 years of a typical hung student's striking power I am sure it will not be the same.
You can take a picture they both may look the same but their striking power will be different. Why is that? Its part of the classical mess.
You have today no different than 40 years back people openning schools that have not achieve levels as describeed in cook books. So these business people will tell students you are not ready to learn specific levels, be patient and pay your monthly fees.
Then you have the real masters that would hurt you, but they work hard to develope what they have, why would they teach a short cut or explain to their students at all. They would like to see you dedicated before teaching you a small portion of their knowledge.
The idea to hung ga is the multi-levels of breathing in the forms. This is if you can find a good teacher.
Hung ga is about power internal & external.