Wing tsun's "Explosive/Extreme return" form is probably developed to train "The return" to basic structure, frontality, balance etc. from "non optimal" positions.

Biu Jee contains of nine sections describing the "return" from various "non healthy" positions/situations if "lack of basic structure".

Biu Jee - "finger pointing beyond the moon" means the idea of "no zone" exploding arms towards the attack'er, without necessarily knowing the form of the attack.

Biu Jee primarily trains/tests frontality during rapid "no zone" movements with possible following footwork, and return from non frontal positions.