If you listen to a lot of podcasts over a long enough period of time (guilty) you'll start to spot patterns. Dying podcasts, for instance (like dying blogs) often have the "sorry we've been a bit quiet lately -> we're back to regular posting -> it's over" three-step death; podcasts about conspiracy theories almost always end up being about crime too, which took me way too long to work out; and narrative podcasts seem cursed to always go down the tubes after their first series.
A few years back, perhaps in a fit of nostalgia for the BBC audio dramas of my youth, I tried to listen to some narrative podcasts. They were largely comfort listening, not actually good, for the most part, but usually fairly pleasant to listen to. I think these are (or were at the time) the 'new wave' of story podcasts, the one before being pioneered by bloody Night Vale (and the legion of Night Vale imitators that I presume must exist). I did listen to Night Vale for a bit but it's a joke that's funny/interesting for a few episodes; it's A Series Of Unfortunate Events: yes, this is an wryly humorous tone piece you've constructed, no, it's not immune from the law of diminishing returns, and those kick in hard and fast.
For said new wave, though, there are an decent number of commonalities (at least with the ones that I've listened to): they're all some flavour of sci-fi/fantasy mystery plot; if they've got a mate who does music you will be hearing a lot of the same three tracks of said mate's music; a lot of them do some sort of playing with the form, whether it's having them solely be audiologs or the show being a parody of NPR podcasts. At the time (2016-17ish), we were still riding high on the Serial boom of narrative nonfiction, and a lot of them were framed as parodies/pastiches of that. (A lot of them sucked at this, but some of them used it really well—The Black Tapes had a gimmick was that the series was meant to be about unusual hobbies or something. They said in episode 1, about paranormal investigation that episode 2 would be geocaching, but obviously they got stuck on the ghost stuff. Then, after the Shocking Events of the end of series 1, they began series 2 with ten minutes of an episode about geocaching. That's really funny!)
The key thing that unites them, though is that, almost without exception, they have a strong, tightly plotted first arc after which they break out the Patreon and s p r a w l. Obviously, having a Patreon is fine—I just think that the point where they get successful enough to warrant one is the point where they lose their focus. Part of it might be the desire to justify their listener's investment—and fair enough, I can well understand that! I think many of them might have been better served by doing a Kickstarter, which would've let them build up a load of funds and then go away and work on a whole series. These things are not built to be The Archers; when they blunder straight into a second series they really lose something.
Archive 81 is a good example of this: it was a guy (for Mysterious Reasons) recording himself listening to archive tapes of a lady talking to residents of a spooky New York tower block, a bit like the one in Ghostbusters. Well, actually, it was his friend who got sent the recording after it all went pear-shaped, which leads to some funny "I'm trying to find out what happened to my friend, if you know anything please get in touch, and share the podcast to get the word out" stuff. Then, series 2 kicks off and suddenly it's "he's in a parallel dimension, and has been turned into a human tape recorder, and, and, and" I know what this is, I have written stuff like this. It's all a bit off-the-top-of-your-head. Some of the ideas are good in isolation, but you're trying to cram them into something that they're not suited to. None of it really hangs together, it's not really possible to picture it.
There might be some way that this stuff could work, but it's not like this. Ars Paradoxica was another one: the dialogue sounds like it was written by someone who'd mainlined Joss Whedon shows for a few weeks prior to writing, but it's generally pretty fun and entertaining. Once it's set up its status quo and done a few time travel stories, though, they shift things around, and the plot and the characters quickly start to get out of control. Even listening to them all one after the other, things got a bit jumbled. There's an ambition there that I don't think the writing and performances can accommodate.
Some aren't completely sunk by this but still fail for other reasons—the Minnow Beats Whale podcasts (which you can kinda consider as a whole because they're all veeeeery similar) often don't fall apart quite as quickly—but they just have too many dangling threads for anyone who isn't an obsessive. Return Home I gave up listening too pretty quickly because it seems unable to decide what tone it wanted to have—though that does lead to a really good gag where the protagonist's best friend is basically cool with spirits causing the townspeople's eyes to go black and speak in ~spooky voices~, to the point where he works out how to get possessed himself. The Bright Sessions took longer to fall off than most by dint of having the majority of the early episodes be two-character dialogues and having a limited number of characters, so everyone gets well and clearly defined (less charitably, it works because it borrowed the format of In Treatment).
The only podcast of this kind I can think to recommend unreservedly is Limetown, a genuinely effective—and, crucially, short (6-part)—series. It was atmospheric, tighly-constructed; it has a bluntness, a brutality that a lot of the the other shows don't, and a clear mystery that is explained satisfactorily, which seems to be the hardest thing of all to achieve. It even had, that rarest of all things, a second series that they took their time on, didn't rush into... and it still completely sucked. Not as much for the reasons that the other shows did—it was just crap, like the first series had been a complete fluke. Maybe these podcasts really are cursed.
Something else funny, looking back at all these, is that many of the bigger ones seem to have had TV adaptations—Limetown got an adaptation on Facebook Watch, a service which is allegedly still going, before being canned after one series; Archive 81 got a Netflix adaptation last year, before being canned after one series; Lore, which I've not mentioned as it's not really one of these, it's a true crime podcast that happens to be about... folklore, I guess, kinda? got an adaptation on Prime Video, before being canned after... wait, two series? For Lore? The podcast my friend and I used to refer to as Snore, or Bore, or Chore because it was so dull? TV execs have no taste.