Beginning writers are encouraged to keep their first novel manuscripts in the 50,000 – 60,000 word range. And believe me, it’s easy to go off on an interesting tangent and usually not as easy to get back to the story at hand.
I tend to think of these temptations to stray as “untold stories,” and there were quite a few of them I mused over that never made it to my series’ first book, The Water Cure.
My main character is a medical doctor, a fact established early on in the book, and one of the stories that I didn’t pursue was having her work as a nurse part time for a woman that some have described as “Arkansas’ first woman medical doctor,” though I’ve seen no documentation for that claim.
Dr. Pearl Tatman is a kind of local legend here in Eureka Springs, and has a unique and interesting life-story. My original thought was to have my character keeping her own records of Dr. Pearl’s “water cures,” getting caught, and having my character reconcile with her by introducing her to the orphaned girl that Dr. Pearl adopted as her own daughter. “Cozy Corners,” the home where they and husband/adoptive father Dr. Albert Tatman actually lived, is operated as a tourist lodging home near mine.
I ended up only alluding to my character’s desire to work for Dr. Pearl, because my word count was already climbing, and this episode didn’t really advance the story or my main character.
In another unused scenario, I would have had this character square off with the charlatan Norman Baker, who claimed cures for cancer and other ailments at the hospital and sanitarium he established in the closed-down Crescent Hotel. She would have investigated his claims and debated whether to help the state of Arkansas debunk him, only to have the question rendered moot by the U.S. government nailing him for mail fraud. Which is what actually happened in 1940.
Another unfollowed trail was with the character who has experimental aircraft experience, not simply tempted to make his way into Nazi Germany before World War II as I wrote it, but actually doing so. Insinuating himself into the Third Reich’s x-planes program, he would have waited to get close to Hitler at a demonstration of the aircraft in order to assassinate him — before thinking better of it. (I had even thought of him helping design and create an underpowered gravity-resistance vehicle for that demonstration; playing off an old conspiracy theory that Hitler was developing flying saucers.)

In the end, I think it was the better decision for this character to simply propose such an operation, while having another character talk him out of actually doing it.
There were several other dead-end trails that established my characters’ participation in actual events in the history of Eureka Springs and beyond, but they seemed to slow the flow of the narrative rather than contributing to the overarching story.
They would definitely have taken the work far past 60,000 words!