It is doubtful any endocrinologist, outside of neurosteroid specialists, could answer this. If they would even have an answer. Feedback mechanisms of allo may have never been investigated.
There is some back-coversion of allopregnanolone to DHP, which acts on progesterone receptors. But sage-217 is only similar to allopregnanolone, so it may not undergo a similar conversion to a DHP equivalent, or the metabolite may be inactive.
Someone else said that perhaps the drug is proposed to be administered in cycles because of a potential for tolerance or shutdown.