Stephen King and Dean Koontz have been getting feedback from people and the market so long that their instincts are razor sharp and they have internalized a structure of stories and what will/wont move readers that they naturally lean on without having to puzzle things out the way a less accomplished writer would.

If you don't have that wisdom, trying to pants something is going to result in writing yourself in circles, contradictions, inconsistencies, incoherence of idea, etc.