In LOCH, Gwok Jing made one of his biggest leaps in martial arts ability after spending months as the prisoner of West Poison Au Yeung Fung. Needing to spar against Au Yeung Fung regularly just to survive, Gwok Jing made his last big martial arts leap in the story...taking him within striking distance of the level of the Greats. Similarly, in ROCH, one of Yeung Gor's biggest pre-Heavy Iron Sword boosts came after his discussion with the Golden Wheel Monk, who advised him to focus on one martial art rather than trying to be a jack of all trades. The advice helped Yeung Gor to advance to a higher level.
Is this a trope of wuxia: that our worst enemies are sometimes our best teachers?