When I did my OW class, the confined water sessions were run the way I see most of them run when I watch other instructors. All the students got on the bottom of the pool and sat, and the instructor started at one end and had each student demonstrate whichever skill was being done, while the others watched. If we got through the skills the instructor wanted to cover in that session, we were cut loose at the end for ten minutes or so of free swimming. The instructor had us all under "direct control", but most of that consisted of demonstrating that we could sit still and not drown.
In contrast, we run our confined water sessions quite differently -- but the technique is dependent on having one or more CAs in the pool, which we always do. The group, of whatever size, is broken into buddy pairs. My husband, the instructor, works with one buddy pair at a time, and the others are free swimming with the CAs. Any skill a student has done for Peter is fair game for the CAs to request, and we do it while the students are swimming.
This has two nice results: The students have a lot of time to practice the most important diving skill, which is buoyancy control, and they finish the class having done many of their skills ten or more times, instead of the one time in front of the instructor that is sufficient for standards. They also don't get as cold.