In all (or most) of Jin Yong novels the hero always find a way to obtain powerful martial arts. Like GJ getting help from a taoist priest from QZ and learning 9Yin or DY gaining knowledge of superior martial arts like 6MSJ and LBWB. But a more realistic and dependable way of gaining power is developing one's internal power over time because one might not be as lucky as GJ or DY.
People like H7G and WCY are probably not even close to Great-level at GJ or DY's age. They probably reached Great-level through the more usual way; through training their internal power over time. But how exactly is this done?