Writing Your Novel from the Middle is short - 86 pages or so. A lot of it is repetitive. I think it would have made a lovely article. BUT, like I said, I think it is going to help me for my upcoming book, so definitely worth the time and 3.99. I haven't read (but do own) Save the Cat, so I can't compare at present. I think a lot of writing advice (just like psychology theories!) is just relabeling parts of a story.
There is a lot in Middle that I will toss out. But two elements for me to keep are the Golden Triangle, as noted, and the Suspension Bridge. He doesn't formally join them together, but I did a rough joining today.
To me, Golden Triangle and Suspension Bridge (aka 3 act structure) are both structural. JSB seems to reference only the Bridge as structural and only addresses its pillars, not the ascend/descend aspect of the Bridge.
Considering Golden Triangle as primarily (or solely) structural, I am inclined to gloss over the midpoint in the book because I prefer static protagonists (there could be change over a series, but not in a single book). Think Sherlock Holmes, Jack Reacher, Brother Cadfael and so on. So my midpoint will be where the protagonist loses all their * and finds the reserves to pull it back together. She might doubt her ability, her determination, her desire to reach a specific end, but she will get back on her feet and go in search of the next lead.
Notable is that Bell says address whichever part when you are ready. Maybe you know the prestory psychology. You've been living with this character and you know her inside out. On a personal level, you want to transform her from X to Z. Knowing her prestory psychology, you can pretty much figure out her midpoint crisis.
Without the Bridge, the Triangle would be of no real use to me. Bell says the First Pillar is where the story takes off - the character from this point cannot turn back and must follow the story to its conclusion. Since passing the First Pillar puts one in Second Act (approximately - Bell says in a novel, it should be around the 20% mark, not the 25% mark of a play), the protagonist must carry on because it would be one or more of the three "deaths" (physical, professional or psychological) to quit. It is also important (in terms of the advice rendered) to include an Opening Disturbance early in the story (I think he says by the 10% mark).
The Second Pillar is about inevitability. That clue that has to be tracked down, leading the protagonist to the killer's lair and so on. It could be a member of the party leaving or joining, some change that makes the end possible or inevitable.
That's my present takeaway based on last night's bleary reading. After reading about the two pillars, I got out of bed and wrote down (by moonlight on yellow paper - surprised it is legible) the two pillars for the book I'm planning. I already knew these events were going to happen, but now I have a better sense of where to place them and how they relate to another.
Oh - one last takeaway. To be memorable, you must show the transformation, not pay lip service to it. And to make it more meaningful, you need to plant a symbol for the transformation early (I believe before the first pillar is reached). I didn't want to write in the dark again, so I put my symbol into the notes on my phone. Now I have to get it all into scapple. :D Also, I need to see if I can put an image of the Golden Triangle Suspension Bridge as the background on scapple.
