@awnlee jawkingI have a different take on "Escalation Boredom"...
Original story is very good, "believable" at least within the "world" of the story; challenges are to scale with the MC. Second story had a dramatic escalation of threat, yet the MC triumphs. Third story, the threat is "Epic" and it is not at all plausible for the MC to defeat such a threat without Deus ex Machina. Or the MC (or team) is "powered-Up" (often ridiculously so) and now the threat must be escalated too...
I preferred Louis L'Amour, Sir Arthur Conan Doyle, or Agatha Christie, and their characters that occur in multiple (dozens or more) books. Challenges varied, and yet were plausible. Louis L'Amour in particular would have dangerous gunfighters, or clever schemers, often circumstances would prevent the MC from just shooting a threat. Enviromental challenges were a staple of his books, and often a potentially more lethal threat to the MC.
Many stories here on SoL are much better than Hollywood "Blockbuster" franchises; in that they build not only in a plausible manner, but they are often a "rollercoaster" in that after a serious challenge, the characters often face a lesser issue, that none-the-less needs to be addressed. Not every problem needs to be "epic" to be engaging.
Grey Wolf in his Variation on a Theme series has his characters deal with threats of rape, then a comparatively minor contest for the student council, or electing a school board member, then taking one of many steps to a secure economic future, then a life threatening situation. Preparing for and engaging in debate contests is made engaging, and at times humorous, or dramatic, though clearly no lives are at stake. But state or national championships are consequential, and when well written are more engaging in some other Marvel movie where they "save the universe" in 90 minutes, again...
The Grim Reaper series is another great example of varied challenges that are engaging, and yet believable.
I believe a major reason that the story The Millionaire Next Door is so popular is that the challenges are plausible, yet engaging.