I think the writer "akaswell" who writes the "Markets and Multiverses" and "A Budding Scientist in a Fantasy World" series has a very firm handle on story engines. Especially in Markets and Multiverses. That series is a slow-rolling serial transmigration story in which the characters are reborn on a different world every 50 or so chapters. (In other words, about the same word-count length of your typical published book.)
There's a story engine of the market and the limited lives count that the characters have before they need to face off against a major threat in order to get more lives or else face the threat of permanent death. Then, there is a plot for each individual world, and the story that runs through all of this in terms of how this whole experience is affecting the characters.