I am 100% certain the best way to improve performance in the sport of Olympic Weightlifting is through repeatedly lifting heavy weights in the competition lifts (Snatch and Clean & Jerk). Call it Bulgarian, Pendlay, Broz, Joe Mills - inspired or whatever, but to lift heavy weights you need to practice lifting heavy weights.
When going through certain phases in training in the old WFW days the training plan consisted of Max Snatch, Max Clean & Jerk, Max set of 3 in the Front Squat almost daily. When the guys would come in to train they would still ask what they were doing that day; my response, “Snatch 180kg, C&J 200kg, Fr Squat 230kg…or as close as possible”
That said, not everyone can handle training in a manner where the goal is to perform only the competition lifts near max repeatedly for day/weeks/months/years on end. Whether it is physical, mental, lack of facilities, lack of motivation, etc the training must be modified to allow them to continue to make progress. This is where the “Transfer Effect” comes into play.
The transfer effect is a phrase used to describe the degree to which a general movement promotes adaptation in performance of a specific skill.
When selecting exercises it is necessary to choose those that have the highest degree of positive transfer potential. To maximize the potential for transfer effect a training exercise must use reasonable levels of movement-pattern specificity and overload. Positive transfer only occurs when the athlete uses exercises that are similar, in terms of load, performance, tempo, and structure, to the competition movements.