I think it's ridiculous to say that people don't usually improve if they take group lessons.
I took semi-private lessons for a few months at the beginning of last year. (Only one or two other riders in the arena). My instructor was nice, friendly, and caring, but she was not a good instructor and I gained some bad habits.
Come winter, she didn't have an indoor. So I moved. I was put with a group of beginners and one more advanced rider.
I was taking group lessons with usually around four or five, at the most seven people in the arena. Fast forward to now, and everyone who watches us agrees that we've all become much better riders. One who couldn't keep her heels down to save her life, now rides a pretty advanced horse and jumps. One who was once afraid to control her horse, now riding more advanced horses who require a stronger rider- and jumping. One who couldn't get her horse trotting very well- now jumping and cantering. All now with competent postures. Me? My posting was horrible, my posture was a bit of a mess, and I was stiff as a board. Now I'm relaxed, my posture is much better, and my posting looks like a competent rider's. I'm now jumping and cantering my excitable Thoroughbred lesson horse.
I find that it also depends on your instructor and yourself. With my instructor, she divides the attention between the students very fairly and productively, and almost always has us riding. (I use almost because she has us do jumping and cantering one at a time right now). The few times I've had a private with her I enjoyed it much less than my group lessons.
They're also much better if you plan to show. You will not only learn how to control horses around other horses, how to not crash into other horses (kind of an important skill), but also warning signs that a fight is going to happen if you don't get your horse's butt moving quick.
Plus, where I live, group lessons are an hour where privates are only a half hour. It's also ALWAYS more for a private. At my place it's $30 for a group lesson and either $35 or $40 for a private, I can't remember. I've found that half an hour of riding now feels like practically no time at all to me, especially when nothing dramatic happens. (Nothing slows down time like waiting with bated breath to see if one of your group members is going to fall off or not).
Over all, while you may get a little more attention in a private I think that group lessons expose you to more difficult and random situations which will help you to improve and gain experience as a rider.
Last edited by Cinder; 10-19-2011 at 06:39 PM.