catsandhorses, YOU are the customer. If you don't like something about your lessons, and the instructor isn't willing to change it, I encourage you to either go private or change instructors. MY money means a lot to me, and I think it does to you, too! =D
The ULTIMATE for me was when DH and our small Cavalry group went to the spring warmups that were held in March by this huge group. Fortunately, they were located only about 2 hours away from us. We could only attend the first days of the 2-day schools--small children at home at the time, you see. Riding in-file, but maintaining proper distance resembled your description, but believe me, maintaining the distance was an imperative since we were riding our own horses, and NOT the lesson horse herd that can (maybe) tolerate somebody riding up on another's horse's back side. Nobody bites and nobody gets kicked maintaining the distance, but you have to ride and be aware at all times, and ASSUME somebody else's horse WILL kick yours, miss and hit you, instead. (There was a "Practical Horseman" article about an international rider getting kicked in the leg while schooling her mannerbly horse, in an indoor arena, and she was off her horse for 6 months recovering.) I tried to teach defensive riding bc of such things.
Anyway, we rode walk, trot and canter, in two's, in four's, and moving back to in-file. We rode obliques, we rallied, we rode left and right turns with about 25 horses on the turns--the horse in the apex barely turns, while the horse on the outside gallops to get around, and everyone maintains dress next to each other. I am teaching my 5 yo geldings to dress now, but we aren't riding them right next to each other--THAT will come. We also practiced dismount-and-fight-on-foot, while one rider held the lead of horse#2, horse #'s3 are linked to each other and #2, the mounted rider circles under the soldiers return to mount. We rode with pistol, sabre and carbine. When you mount with a carbine you must "choke" yourself with the strap so that the carbine doesn't whip past you, hit your horse and possibly frighten him or just make him move off while you are mounting. Similarly, you must remove the carbine from the leather "boot" before dismounting, else you can be hanging, hooked to the saddle, another dangerous position. There is SO much to do that you forget to check your seat, your feet, etc., and just make your horse go where you want him to! The IL 7th Cavalry, the group that sponsered the event has dissolved, but THEY spent the time studying the Army Manual, and had puzzled through sections where the language and customs of the time made the manual difficult. They were quite a resource. Learning these things really whetted my appetite for Dressage, which is, of course based on European Horse Cavalry, along with 3-Day Eventing.