A martial art should already be 'complete'

Unlike fighting, self defence requires the student to finish the opponent off decisively.
There can be no drawn-out combat.

The exponent must be capable of rapidly, spontaneously switching tactics and skills.
Trading blows is time-consuming.
It is necessary to adapt, change and improvise constantly.

Skill in all three areas of combat are necessary: chin na, jing and shuai jiao.
In self defence, the situation is unpredictable and there are no rules.
You must incapacitate the attacker immediately.