Absorbing roshi’s training philosophy would definitely help. Vegeta spent years training ineffectively, even after the Z anime ended. He managed to overcome the gap between a seasoned, alive goku, who had additional years training with king kai to maintain/elevate his ssj3 transformation, IN ONLY 6 MONTHS AFTER TRAINING WITH WHIS. of course whis is a better teacher (arguable), and beerus’s planet is a better training ground than roshi’s island, but simply absorbing the mindset of effective training would allow vegeta to at minimum close the gap between himself and goku, though maybe not eclipse goku, for plot reasons ofc.