Last semester in the twelve weeks of my online class, I focused him on pacing. What is the best pacing for a mystery? What elements keep the momentum going, the tension high? What drops tension, and even distracts the reader?
I asked him to study different aspects of pacing, such as dialogue, character description, and setting. How is each used for best emotional effect?
This writer has improved tremendously in the months we've worked together. But he still can "frontload" his chapters with too many setting details. I wanted him to see how they slowed the pace of his story, and begin to choose the specific details that wouldn't derail his readers.