Also got the report back from the chiro today. His SI and lumbar adjusted along with right hock right knee. Hips felt great and she’s super happy with his neck muscles and said he feels more comfortable through neck and shoulders.
Posts 28 and 32 are very helpful.
OP, your horse learns absolutely NOTHING while lunging in side reins or a neck stretcher. He is not at a point where you can work on riding him in a frame - he is not responding correctly to simple requests such as go and move left or move right. He’s got some holes in his training that need fixing or you will continue to have problems with him. You are having very simple basic problems with him that are easily fixed, but you slap him in gadgets and make him work on the lunge, which does nothing to solve the problem.
You need to understand WHY this horse is acting out. It is NOT because he “has to work and bend and use himself properly.” He is objecting to something specific you are doing, and when he throws his head or leaps then you stop doing it, so the head throwing and leaping then becomes the correct response in his mind. Bending and using himself properly is an algebra question and your horse has holes in his basic arithmetic. Would you get angry at a kid for not understanding an algebra question when the kid doesn’t know the basics?