I am sorry, this is Dynasty, is it not? I may have experience with het works, sure, but it is obviously not a focus of mine. That being said, your exceptions don't matter. I could make a list of 100 het romance anime that are not complete in a 12 episodes season. Even more if we add non-romance focused ones. What does throwing around names prove? As usual I have to note that you have tunnel vision. And it appears to me that you are far more knowledgable about het works than yuri every time we talk. Not that this is a flaw or anything, enjoy what you will. It just means that often you seem to be hyper-focused on the things you are familiar with over a broader perspective.
Is this what they call "projection"? You're the one who decided to invoke comparisons to het in the first place, if you're not knowledgeable enough to back up your own assertions maybe stop making them?
Yuri has little to do with Shoujo romance? Except a majority of early yuri manga used Shoujo tropes, Shoujo artstyles and dynamics. The distinction only came about slowly. I suppose there are two schools of thought there of course, one being Shoujo-like yuri and the other being Class S style yuri, both birthing different aspects of the genre. But tropes like the "handsome school prince" who pins girls against walls and crossdresses etc. are 100% steeped in Shoujo origins, where the girl first and foremost had to replace the role of the boy.
AFAIK a lot of early yuri was tragic. And don't get me wrong, I love dramatic shoujo here and there (Ai Yazawa is one of my favorite mangaka ever) but I'm talking more about bubblegum romance here. Otherwise... I'll give you that the "princely girl" came from shoujo but more often than not she's not even gay. Ouran High School Host Club gave a "prince" character a reverse harem. I wouldn't consider them a gender swap either though I'm sure they've been used that way.
In your previous comment you asserted what you consider the "bedrock" of yuri works, but you failed to mention any of the dynamics that are part of this side. Beyond the more recent "gyaru x shy glasses girl" tropes that you brought up, there have been the "Onee-sama/garden of lillies" works or the "tomboy x sheltered lady" pairings etc.
Nobody thinks Class S is actually yuri these days (I hope) and no yuri LNs I know of are this insipidly stretched out as you claim (with the exceptions being those which dont actively focus on romance and... AdaShima, but just because AdaShima is a unique case of Iruma's madness).
I don't believe AdaShima has face sitting but I was definitely thinking about it when discussing dragged out LN. And going through an exhaustive list of yuri tropes was never my intention either; that's a conversation for a different thread. As far as Class S though I'd assume people still consider Maria-sama ga Miteru yuri, which was pretty much pure Class S. It casts a really, really long shadow over modern yuri, though at least the more problematic implications of Class S were lost to time, though I don't want to diminish what it was for its time here either.
Being firends before being lovers is literally what 90% of Japanese romance is like though.
...but you just admitted het isn't your focus in a previous paragraph so you're basically pulling numbers out of your ass. And you don't like examples either so I'm not sure how to respond here. If your point is that 90% of yuri romances start as friendship that's basically my criticism of the genre and why I'm talking about its roots in Class S and relationships that overemphasize friendship in the first place.
It feels like you're just trying to derail and score some internet points here but the discussion I thought we were having was 'subtext vs bait vs slow burn' and because I know yuri relationships have historically been a 'road to nowhere' the burden is IMO on the slow burn to prove its going to be different. If it can't really do that in one anime season I just don't see it any different than bait, though Class S is probably a better label.
To answer your point(lessness) though I guess I will give you that childhood friends are really common in het but they tend to be unsuccessful in love. I'd give them like a 10% success rate with plenty of memes about the childhood friend losing. I know very little about BL (aside from some BL bait here and there) but I got the impression rivalries were a more common basis for a relationship than friendship. Maybe I was mistaken.
I mean that a happy ending is literally listed as a requirement by the Romance Writers of America (I'm aware we're talking about Japanese media, but it's more or less the same there):
Ehh... have you ever looked up MAL ratings for the "romance" tag? There's an overwhelming number of tearjerkers at the top; stuff like Clannad, Your Lie in April, I Want to Eat Your Pancreas, etc. And Makoto Shinkai has made a career out of scenes of longing (between two people who barely know each other, mind you) against the backdrop of an immaculately rendered golden hour sky.
Don't get me wrong, there's still plenty of "happily ever after" but Japan really seems to favor the bittersweet as well.