The point of feedback, after all, is to develop the designer's judgment, so asking questions to help her size up her own work helps her grow not only as a designer but also as a communicator and visual thinker. If you want somebody to meet standards, follow style and continuously improve, you have to make the feedback process as much theirs as it is yours. Tearsheets won't do that. Tearsheets turn leaders into judges, not partners. Giving feedback is time-consuming.
Relationships require a front-end investment of time.
Leaders should have thorough, exploratory conversations with each staff member as early as possible in the relationship. You may also want to share your own values as a visual journalist and leader. But your main job is to listen, and you may need to set aside an hour for each of these interviews. That may sound like a lot, but these talks pay off in a big way. They communicate to staff your commitment to them as colleagues, not just your interest in their work.