Question: For each signpost are there four drivers, or one driver per act serves all the signposts. I mean to ask, say it is decision driver, is there decision taken in mc, ic, mc/ic, os all the signposts. Or the driver is just for the OS and rest all are reactions. Answer:
Generally, the drivers are part of the overall throughline, as are the 8 essential plot elements. This is not always the case, but it is most common.
The key drivers are the five
turning points which mark the beginning and end of each of the four acts. In other words...
driver 1 --> act 1 --> driver 2 --> act 2 --> driver 3 --> act 3 --> driver 4 --> act 4 --> driver 5
Each of these drivers represents a change in direction for the story. Driver 1 is often called the inciting incident, because it is the event without which the rest of the story would not occur. It establishes the problem or imbalance that must be resolved. The 5th and final driver determines ultimately how the problem is resolved and what the outcome will be.
You may also have other instances in a decision-driven story where decisions drive actions, and these may occur in the other throughlines, but usually it's best to let them take care of themselves rather than plotting excessively. In other words, they are not essential.