People who buy action novels are impatient in a good way. They want to be in motion by the end of chapter one, and they notice quickly when a scene stalls.
Chapters stay short and end on a question or a turn. Set pieces escalate instead of repeating, so the third fight cannot just be the first fight with different scenery. The hero must be competent, but never safe: victories should cost something, and the antagonist needs real power over the plot.
Readers also want clarity. A reader who loses track of who is where during a chase stops enjoying it. We draft action sequences in plain, concrete verbs and check each one against a simple map of the space.
Dialogue stays lean. People under pressure do not give speeches, and a line that sounds like an announcement usually belongs in the cut pile. Backstory arrives in short pieces, usually one or two lines at a time, dropped into the quiet moments between scenes, never stacked up in front of the action.
Finally, there is the payoff. A big ending that ignores the promises of the opening feels like a cheat, so we plan the last act before the first draft begins.