It's called "willing suspension of disbelief."
That's what readers need to have in order to read and think fiction as reality.
The more believable the story, and the better the writer, the easier that "suspension" is.
The Outcasts starts of very well, but three quarter of the way through this western, the harder it got to suspend my disbelief.
Won't spoil the plot by providing details, but, in spite of a good research and an interesting story, credulity gets stretched and stretched and finally, 50 pages from the end just goes... SNAP!
And it was no longer worth the work.
Worse, right near the very end, one of the very big anticipated plot "payoffs" remains...unresolved!