In education who has been a manager realizes that managers need a strategy or direction. The problem is that they usually have no control over the big picture. Likewise when instructors walk into a training session with nothing more than their expertise. They are practicing crisis management. Most often they will be forced to react to issues as they arise and will have no certainty as to where they will eke them Just knowing the material is not enough.
Experience helps, to be sure, but planning is essential unless, of course.
Expensive to design, these lessons are questionable in their effectiveness. They certainly ignore the benefit of an instructor's experiences in the subject area and the value of the instructor trainee dialogue. When you were a student you may have thought your favorite teachers just walked into the classroom and spontaneously conducted a lesson. Some probably did, but most of your teachers used a plan, whether management of learning. Anyone you and training, the instructional management plan is called a lesson plan.