I guess one person's fun theorizing is another's hurt brain.
To me the whole trilogy really does work out now.
1. Rey is a Palpatine unceremoniously disposed on Jakku by her parents to get her as far off the Emperor's radar as possible. Circumstances were so dire that they could guarantee very little of her safety beyond simply hiding her away.
2. Palps wanted a new Force sensitive body where he could transfer his consciousness and power of all the Sith but he couldn't find Rey so used a created proxy (Snoke) as a placeholder figure head of his new Empire with Ben Solo serving double duty as his main henchman and also sweet revenge by corrupting the family of his hated enemies. Since Snoke was just a puppet the "only two" rule of murdering your master and then being possessed by their spirit didn't apply.
3. Palps possibly created Starkiller Base as a red herring to divert all Republic/Resistance/Jedi attention to a single place far from his new super fleet and body. He may have even anticipated it being destroyed just so that he could laugh when he then obliterates hundreds of Star Systems at once while the Rebels are celebrating.
4. Once Palps (as Snoke) learned of Rey he fell into his usual routine of playing both sides against each other and instructing one side (Kylo) to kill the other (Rey.) This was for his own amusement but also as a test to see who would win or whether they'd join together. If they join then he can suck their power and essentially restore his own body (which obviously ended up happening) and if one kills the other then he just takes the body of the winner.
5. His downfall of course is that once he was fully restored it then became a straight power vs. power fight of all the Jedi vs. all the Sith that ended in a stalemate with both Palps and Rey killing each other.
6. Both dead, Palps is gone for good while Rey gets restored by Ben who transfers his life and takes her place in death.
The specifics of Palpatine's Sith magic that allowed him to live on and return are of course not fully spelled out (other than it being an "unnatural" process) but I'm okay with it. I guess I like the double layer approach where on the surface it's just a straight story about a small group of good guys who must overcome the manipulative sorcerer overlord (which I know general audiences are fine with and couldn't care less about any specifics beyond that) while us old school crazies can speculate and connect dots as to what was "really" going on with a couple of those key scenarios. That's all part of the fun for me (in case you hadn't noticed, lol) and I really do think that they did an admirable job of providing a strong enough through line that does seem to be for the most part logical and internally consistent.
Everyone's mileage will vary on that of course.