Lines of Succession started out as a short novel, exploded in a rewrite to over 120k, had a plot hole you parallel park a semi in and ended up about 90k when I fixed that.
Originally, this was a typical fantasy story in the Chosen One vein, with the tweak being that the Chosen One was actually fraternal twins. The boy was a mage, and the girl was the more athletic sort. Talking it through with a pal of mine, she suggested that the Chosen One trope had been totally overdone and suggested I could do better.
So, back to the drawing board. As I reconfigured the plot to lose the Chosen One trope, I also found no use for the magic, so that also landed on the cutting room floor. Instead of the heroes slowly gaining power for themselves, the heroine had power dropped in her lap ... but only temporarily. She had to hold the throne for her older brother.
After that, the majority of the changes were to the names of the secondary characters to arrive at a set that didn't sound or look like the same name as someone else in the tale and toning down the accent of one of the secondary characters. I have a tendency to completely overdo accents because in the first draft, I write them how I hear them. Then in subsequent drafts I have to back them down to readability.
The plot hole problem? At one point, the court physician tells Elaina about a nun who has a cure for blindness in a convent in a country on the far side of their enemies. Elaina's maid and the lieutenant of the guards head out to go meet with this nun, but when they get there, they find out they'd been had. This reveals who the actual mastermind of their adversary is. They race back toward the capital, run into a few misadventures along the way and arrive at the castle ... and do nothing with the information. *facepalm* Oops.
My choices were to rewrite the entire back third of the book or remove that subplot about the nun with the possible cure. Although that subplot was most of 30,000 words, it had to go. I still have it in old drafts and saved into a separate file. I will likely turn it into a short story at some point, but for the purpose of this book, it had to go.
The sequel, A Suitable Arrangement, has bee drafted, but it's a huge monster, and there a major parts missing in the back half of the book. Most likely, I'll rejig some bits and split the story into 2 books.