Breaking trail on the Great Ring - which planes need more adventures?

tl;dr: are people going to the same cardinal iconic planes because the adventures exist or because they prefer to go there?

As part of thinking about a potential new Planar campaign I had a notion about visiting the lesser known planes. I wanted to test whether the planes we hear less about are unpopular or just have less adventures available for them. To get an idea I looked at the Elderbrain survey and compared that to the numbers of adventures available for each of the planes on DrivethruRPG and DMsGuild.

First thought was - do people have a specific preference for where to go on their planar adventures? According to Elderbrain just over half do have a specific preference and of the rest ~1/10 don't like planar nonsense at all, ~1/3 are happy to walk the Great Ring to anywhere.

To try and get an idea of the popularity of each of the planes as a site for adventures, I counted up the number of Dungeons and Dragons system adventures with the relevant plane in the description for each plane. Since this is somewhat crude I was very surprised when the relative popularity of the different planes in both survey and available adventures tracked so well for the most part.

The Elderbrain survey had one major omission - the neutral axis of Mechanus - the Outlands - Limbo. Sigil is included and tracks similarly between the two sources.

I used 'demiplane' as a proxy for 'unique plane' since many adventures have pocket dimensions and the like but the poor match suggests this is not correct.

I was very interested to see that the number of adventures available for the Lower Planes - was apparently much, much higher than interest in playing there with the exception of the Nine Hells. I am unsurprised to see Feywild placing most popular and having adventures available - apparently Wild Beyond the Witchlight is well targeted for the zeitgeist.

All told this suggests an assumption in adventures of 'the Outer Planes as high-tier dungeons' with raids into Hell and the Abyss as the archetype - and a gap for adventures visiting the other planes. I suspect exploration style adventures or ones with a focus on the visiting places with less immediately hostile inhabitants could be popular. The Lower planes gather 3 times as many votes as the Upper for "Which planar settings do you enjoy playing the most?" but there are 12 times as many Lower planar adventures available, suggesting some potentially un-met appetite for adventures outside the Lower Planes.

My hypothesis coming to this was that there would be lots available for the cardinal Lower planes - the Nine Hells and the Abyss - and the rest of the Lower planes (Acheron, Gehenna, the Gray Waste, Carceri, Pandemonium) more or less forgotten. Instead I was surprised to see that the non-cardinal lower planes seem to be less popular and have a broadly appropriate number of adventures available. What appears to be off radar are the neutral planes of Mechanus and Limbo - which is surprising as I thought Modrons were more popular than that. I was not surprised to see the upper planes are less popular but the closeness of the ratio surprised me.

So there looks to me to be a gap for upper planar adventures and I would not attempt to stand out by setting my next planar piece in either the Abyss or a demiplane. To my eye it is a wonder that noone has made something of the floating bergs of Ysgard - there is no adventure to be had in Valhalla? Really? Similarly, Bytopia, Mechanus and Gehenna seem to cry out for more adventures.