So.....what was rachel's master plan again?

So, find boy with exceptional compatibility with lots of different bias factors. Use boy to make 3rd gen God Eater squadron. Turn boy into singularity for devouring apocalypse.

Then stop 3rd Gen God eater squadron from stopping rachel into turning boy into singularity for devouring apocalypse.

Wait, why am I trying to trigger a devouring apocalypse again?

Is there any real purpose to Rachel's seemingly back and forth dumbshit master plan or is she just insane?

At the very least, Johannes had purpose in his actions. Though mad, you would understand he isn't a comically evil megalomaniac.