On why Biggs says that the SOLO Extended Abstract level is “outside of the learning cycle”:

I agree that in sanda (散打; sparring) you learn to relate the moves you were taught in taolu (套路; forms), and you can reach a deeper, more abstract understanding of the art of Wushu (武术).   You might watch a video of the fight and analyze what you did, and relate your moves to what you were taught.

When a student has the engagement+effort+talent to reach the Extended Abstract level, perhaps they may create new combinations that are original, not something they were taught.    They may even create an entirely new “style” of fighting, such as Changquan (長拳 or Long Fist), or Nanquan (南拳 or Southern Fist).

How can teachers require students to go beyond what they have been taught?

As Biggs said: extended abstract thinking is easily recognized, but difficult to specify.

This is why Extended Abstract is considered to be “outside of the learning cycle”.