Why exactly do negatives entities inevitably need to switch polarities?

[Patrick]

When a STS entity want to change polarity, do they have to redo 3rd density and start over or can they switch within the density they are currently in.

Excellent question !

Ra seems to say that they have to redo the work, but it's not clear if that means they must start from 3D again.

Questioner: Then did they continue striving to polarize negatively for a fifth-density negative harvest or did they do something else?

Ra: I am Ra. They worked with the fourth-density negative for some period until, within this framework, the previously learned patterns of the self had been recaptured and the polarity was, with great effort, reversed. There was a great deal of fourth-density positive work then to be retraced.

But here they say that the switch is instantaneous, but that does not mean that the accumulated Karma is instantaneously released.  There might be work to do.

Questioner: Well, then let’s say that when Himmler, for instance, reaches sixth-density negative at the beginnings of sixth-density negative, at this time would it be [the] case that an entity would realize that his higher self is sixth-density positively oriented and for that reason make the jump from negative to positive orientation?

Ra: I am Ra. This is incorrect. The sixth-density negative entity is extremely wise. It observes the spiritual entropy occurring due to the lack of ability to express the unity of sixth density. Thus, loving the Creator and realizing at some point that the Creator is not only self but other-self as self, this entity consciously chooses an instantaneous energy reorientation so that it may continue its evolution.

Questioner: I assume that an entity on either path can decide to choose paths at any time and possibly retrace steps, the path-changing being more difficult the farther along is gone. Is this correct?

Ra: I am Ra. This is incorrect. The further an entity has, what you would call, polarized, the more easily this entity may change polarity, for the more power and awareness the entity will have.
Those truly helpless are those who have not consciously chosen but who repeat patterns without knowledge of the repetition or the meaning of the pattern.