I've figured out why finally!
[This morning Kenchu was almost inconsolable. He always has pain around his ears and jaw (both are full of pus and smelly mucus - his mitochondrial disease is around his head). I tried all the remedies from Lach 6 to cm, and then I remembered how much they love Crotalus. I only had the cm and he drew it more than the Lachesis. One dose and he's sleeping peacefully. I should get Crot in lower potencies as well. I wish I had thought of it when Ancient was suffering - but his intestines were the problem and he wouldn't draw any Lach 6 and I was overwhelmed by the number of remedies he was drawing. Oh well, it's always after that I wish I had had the time to do better.:/
The snake remedies are Lymphatic and help drain away bad lymph. Why it starts firing only after the New Moon is still a mystery to me, but the cycle the body works on seems to be the First Qtr to Last Qtr, rather than a true New Moon to Full Moon. Maybe lymphatic drainage is mild around Last Qtr - New Moon and then becomes more urgent and forceful after New Moon.
The sea remedies come just after the Full Moon probably because the water balance in our body is skewed. Being sea animals originally (and mitochondria being closer to sea bacteria) the effect of the full moon on the body is to increase acidity and inflammation like beached fish if not soothed by the water and sea remedies. The water elements and sea animal remedies kick in to reduce the scrofulous burn and prepare the body to drain off the lymph in the next cycle. That's my explanation so far.