Unfortunately, a great number of pros don't know how to structure a group lesson so that it meets two criteria:
1. It provides understanding of how a shot, stroke, technique, strategy, etc., should be executed within the capacity of the groups' abilities
2. It creates a means in which each player has ample opportunity to replicate said shot, stroke, technique, strategy, etc. in a way that the player moves closer to success in such replication.
Obviously, there is much more to successful group lessons: personality, equipment, space, etc.
I always enjoyed group lessons far more than private lessons. I loved large groups, even taught a single group lesson of 75 players on one court. Loved the challenge of meeting the needs of such diverse groups and having them leave the court feeling like they not only had a great time, but that they sincerely learned something that moved them closer to playing at their potential.
Anyone looking to see how I successfully ran such programs, (in addition to coaching one of the all-time most successful tennis teams in the U.S.), can read my 400 page, "Coaching Mastery" which also recounts my father's success of creating a team that won 399 consecutive team league matches in Southern California. (The book is a top-seller here at Tenniswarehouse.com)
Clinics can also provide the opportunity to see how others hit, (good and bad), and allow you to evaluate yourself within such criteria.
Dave Smith: Author, Tennis Mastery/Coaching Mastery;
Senior Editor, TennisOne; Dunlop Master Professional