Coaches at almost every level eventually get hit with the numbers problem. One coach may be responsible for numerous teams or extremely large teams. I know several college coaches that handle 20+ teams as the only coach. I also know other coaches who work with football programs that need to handle groups as large as 50 at a time.
One thing that I don't think gets stressed enough to new coaches is the value of simplicity. They are bombarded with information and are eager to implement what they know. The problem comes when their program is not doable given the numbers of athletes/teams. In this situation the coach needs to look at these situations the same way a doctor looks at an emergency room. The most important thing become triage, what is most important and how can I get the most progress out of the most athletes without risk of injury.
The most effective approach to running individual workouts is to know how you are going to organize the athletes. This is mostly done through stations, grouping, and timing. Keep the exercise selection simple to minimize the amount of teaching or corrections that will be needed. One of the best ways to manage a room that often gets left out is having a pre-workout meeting. Before they start, get the entire group together, explain how they are going to be split up, how and when they are going to move from exercise to exercise, thoroughly but briefly explain the entire workout, and quickly demo each exercise. This type of meeting will solve most issues that would arise and prevent problems before they happen. It also give the athletes a chance to get any questions answered ahead of time.
Doing these simple things can make a world of difference in the effectiveness of strength and conditioning training sessions. Just remember the best strength coaches are the most organized ones.