Shticky Guy -“Health We cannot daven for rain while having a chiyuv to eat in the sukka. So we wait until AFTER we are no longer mechuyav to eat in the sukka before davening for rain. This is why we do not say Geshem on Sukkos. And that was my exact question. If we are mechuyav to eat in the sukka on shemini atzeres then surely we should wait until simchas torah before davening Geshem. But davening on SA seems to support the minhag of NOT eating in the sukka on SA. Please answer that.”
Yes, this was the answer I was thinking of. But you took it too far. We really should Daven for Geshem on Sukkos, but we don’t want it to rain. But on SA there is No D’oraysa to sit in the Sukkah, at the most a D’rabbonon, so we won’t delay Davening for Geshem any longer.