Whenever they get a sorcerer of a new type, they study him as intensively as they can. The point being to learn what the nature of his magic is and reproduce it as reliable as they can, in the hands of anyone who can study, not just the (un)lucky flukes.
Which means that the story where a sorcerer knows the magic that the heroines' father uses in another story must come before that other story.
Because the first ambition of anyone who practices magic is to drain the magic out of it and get reliable results.
