"We all know that the lady lowers the heel to the floor only as the moving foot passes the standing foot."
This is a common misconception based on sloppy reading of the technique and insufficient attention to the role of technique in producing the desired overall dancing.
1) in a plain WALKING ACTION as documented in the introduction of Moore's book, danced with NO RISE OR FALL, then this would be true. But that's not the case in this figure. Instead, a descent is occurring, and that will necessarily make the details of action different than in the case with no rise or fall.
2) If the lady had foot rise, this would be the traditional timing for when the foot rise would be lost. But she does not have foot rise, so it's not literally mandated that her foot go flat at this point and not before.
Now, speaking more generally, I'd refer you to my post of yesterday on when the feet go flat / foot rise is lost in small traditional vs. large modern movements:
This depends on the size and dynamic of the movement that the dancers wish to execute.
With the limited altitude change and smaller movement of traditional dancing, much of the descent is complete by the time the foot is flat, so this will occur late in the overall descent, as the feet are passing.
But with todays larger and more dynamic dancing, the majority of the overall altitude change will occur in the legs AFTER the feet are flat on the floor. Since the lowering out of the foot rise marks only the beginning of the overall descent, it will have to be complete earlier, usually before the feet pass.
The technical rules underpinning both methods are the same; but applying the same rules to two different situations (two different desired outcomes) generates two different sequences of action.
"Anonymous . We are not refering to different situations . "
The different situations are the range of possible desired characters of the dancing - traditional, small and high in the legs, or modern, large and descending very low into the knees during the lowering. Applying consistent underlying rules of technique to both cases dictates that the sequence of actions will have to be different to create each desired outcome.