Flexibility routines in kungfu are to make sure you don't stretch. They are feedback! The purpose of daily flexibility routines is not to create flexibility. The purpose of these routines is to let you know you went too far in your practice the day before. When you stretch too far you'll know it because the next day, or sometimes the day after that, you will feel pain where you over stretched. The lower back and the sacrum are common places people feel this pain. I've known dancers that lived with pain from over-stretching everyday of their careers.
If you go through a flexibility routine pain-free, you are doing it correctly. If you feel stress in you're joints you are not.
When we sleep well, our bodies naturally draw in towards the center. If we don't sleep well the whole body is looser. In general people are looser at night-time classes and tighter in the morning. Sleep is an extremely important factor in flexibility.
The story goes that my first teacher's teacher, Kuo Lien-ying would reach over to put his chin on his toes every morning before getting out of bed. Toward the end of his life, he cried when he wasn't able to get his chin on his toe.