Studying a martial art in a group rather than by individual instruction has its benefits. While individual training may help the students correct specific problems, group training encourages students to work harder to become a good as the group in general. While a student may want to quit training when tired, not wanting to look bad in front of the group will cause the student to keep training. Peer pressure is a powerful thing.
A 1989 study by Bell and Yee, Skill level and audience effects on performance of a karate drill, found that an audience enhances the performance of a well-learned task, whereas performance is impaired for a poorly learned task.
A 1999 study by Layton and Moran, Effect of "group spell" upon Shotokan black-belt performance of Heian kata, watched black belts performing kata as a group. They found that even though the participants had refined the kata over years of practice with their own timing, the timing became more consistent when the kata was performed as a group.