Maxim: Belly dancer kicks with her ass from extreme point toward straight spine, not from straight spine position toward curved spine position.
Kick with ass from extreme position toward neutral. It may pass the neutral position toward oposing extreme point. That is called rebound, catching the energy.
Rebound can be caught by the opposite kwa (left-tight) or with both (central channels, both kwa working simoultaneously)
If you stand on one leg, that is extreme position. That means kwa is already loaded.
Between beginning and end position of a move there is a dead transition, where kwa is not loaded. That is generally referred to as ‘double-weightedness’.
Kwa movement is small, two inches from one extreme to other. Less is better. Or heart hurts. Though it has to be full and leading.
Analogous yin-yang training applies to breathing practice.