Adventure Time was the channel's biggest hit and while it was allowed to run 10 seasons, some of them exceptionally long, even it is getting screwed in its final season with random airings of blocks and little to no promotion, and constant hiatuses just to push out a batch of episodes.
And Regular Show we didn't know was ending until about a week before it happened. And though a different channel, Gravity Falls was constantly screwed too and similarly, didn't announce its end until the last minute.
See also how Korra got screwed around with Nick not ordering seasons until after they had finished a year, not advertising, pulling the show and only airing it digitially, pulling an episode's budget at the end of production forcing a clip show…. or when ABC cancelled Reboot and it had to keep going in Canada to get to its amazing thired season and then was cancelled again before finishing season 4...it happens all the time.
See also shows cancelled before they were ready to end and had a cliffhanger finale, like Sonic SatAm or Spectacular Spiderman or Teen Titans, or shows that were straight up only half done like Pirates of Darkwater or new Thundercats... or the way shows like Samurai Jack or Mysteries Inc had their final episodes held and stretched over ridiculously lengthy ammounts of time. Hell, Calamity Jane only ever aired its first three of thirteen episodes.
It's not just a Steven Universe problem, or even just a Cartoon Network problem. Animated shows get treated like crap all the time, because they take so long to produce and get greenlit so far in advance, it's possible for new execs to come along and completely hate them by the time they ever even start airing.
As for the 11 minute format? That format is fine, in theory. It forces you to cut all the fat and get right to it. In theory, the advantage of it is you can take an old 26 episode budget and get 52 episodes out of it, and so air a new episode every week all year. And in theory that's great and it was fantastic when Adventure Time basically did that model.
It's not so great when they instead decided to have multi-month gaps and then just binge 5-8 episodes in a week and then go to another drought, it completely defeats the purpose of the format.
What a huge bummer. SU is the only CN/Disney show that I ever got into but I'm surprised that it's so common.
This might not be an apt comparison, but adult animated shows get wildly different treatment. The Simpsons, Family Guy, Bob's Burgers (feels kinda wrong to lump that one in alongside but whatever) and Rick and Morty keep season contracts and have typical off seasons. The one exception is Rick and Morty which takes a long time to produce but Dan Harmon recently played hardball with the network and got them to agree to an "all or nothing" four season order. I'm not crazy about Rick and Morty on the whole but you gotta respect how Harmon went to bat for the series longevity.
So, even though my understanding of this is narrow, I still see that and then look at the crewniverse and wonder why they seem to let the show suffer as much as it does. Maybe not nowadays, but there really was a time a couple seasons ago that Sugar could have leveraged for a similar deal that fixed the formatting/scheduling issues and then some. I don't get the impression that crewniverse hates working with CN or anything, but they must have been reading the majority of the fanbase that has always been bothered by this and they've never really spoken up or been transparent about it. I'm really just trying to wrap my brain around the whole thing.