After successfully becoming a disciple, Lu Wuyan served his master for a full ten years before he learned some alchemy techniques and mastered some very ordinary pill recipes.
However, his master's famous pill recipes were not going to be taught to Lu Wuyan.
Why? Because the master had other disciples, and the one who would truly inherit all the recipes was the direct disciple, who would carry on the master's surname.
Lu Wuyan, as someone of a different surname, was not going to be given the true pill recipes.
Later on, when Lu Wuyan gained fame, it was in part due to the art he learned from his teacher, which gave him a solid foundation in the basic alchemy techniques. On the other hand, the key factor was that Lu Wuyan had a family legacy of pill recipes.