This book has a lot of useful advice, but it's also espousing a philosophy that I think is poisonous to the game, and that's an attitude that prioritizes heroic fiction over player agency. From Chapter 24:
Tweaking combat is one way to change a beat from fear to hope, or vice versa. You can do so by adding monsters to make the fight harder, or removing monsters to make it easier. If the characters have been having an easy time of it, they might walk into a room full of armored ogres training and sparring. If they’ve been having a hard go of it, maybe they stumble across a lone ogre, face down and asleep in her plate of raw meat.
This is the sort of thing that saps player agency and devalues player skill. If they've been having an easy time of it, it's because they've been using lateral thinking and clever tactics to efficiently defeat obstacles. Why would you punish that by throwing extra obstacles at them? If they've been having a hard time of it because they tried to Leroy Jenkins their way through the dungeon, why would you reward that behavior by smoothing the path for them?
In fiction the hero always barely wins the last battle, bloodied and exhausted and depleted, because that's all scripted and the author is the only one with agency. Trying to recreate that in a role-playing game sacrifices all the strengths and freedom of RPGs to turn them into a mediocre imitation of a book or movie.
There are a lot of good suggestions here-- I'd encourage anyone to read chapters 8, 15, 21, and 22. Just tear chapter 24 out of your copy of the book entirely and forget it ever existed, and the remaining chapters comprise a 4-star resource.