However, the high-end secret manuals of the Flower Planting Family, even if recorded in books, are generally written in code. Without knowing the correct decryption method, one could not even begin to cultivate the methods described therein, let alone understand them, even if they held the original manuals in their hands.
Furthermore, some of the Super First-Class Martial Arts are predominantly not recorded on paper but are passed down through word of mouth from master to disciple. Even then, most masters do not impart all of the secret manuals to their disciples at once. Instead, they teach the techniques layer by layer, according to the disciples' cultivation speed.
The advantage of this approach is that it prevented disciples from becoming distracted by ambition and thus succumbed to cultivation deviation. More importantly, it also allowed them to increase their control over their disciples.