well, lets take away the term "see saw" and ask, do you ever slide the bit in the horses mouth? If you "sponge" what are you doing? how about a "demi arrete" where you use on, or both reins to move the bit up off the bars of the mouth onto the lip? what do you so if you want the horse to simply yield the poll, without changing bend? What do you do if you want the horse to simply change bend, without yielding the poll? How does the action of the hand differ.
I have had people swear that they trained a horse from never carried a rider, to GP without ever pulling the rein. This, i do not believe.
The essential thing is be be able to carry your hand, or move your hand, with complete independence of what the seat or legs are doing. I have seen dressage riders with a great seat, when on the contact, suddenly look like jack in the boxes if the contact is dropped, so actually they are relying on the contact for balance.
sometimes the aids can whisper, but there are times when a whisper will not do.
There is the whole, never rotate the wrist thing, yet when a horse is trained, rotating the wrist is what brings bend or turn rotate in, the horse bends,m rotate out, the horse turns, usually just a little. learning this teaches a rider not to pull back to accomplish either
I have a friend who rode with a Western trainer and we sometimes trail ride together. When she talks about "framing him up" (her horse), she shows me what she was taught, which IS see-sawing - pulling one rein back, then the other .... see-saw, see-saw until her horse puts his head down and then that's it - mission accomplished! There isn't a "feel" involved, which is what I think you are referring to, chisamba, and there's no relation to the rest of the body.
I have had instructors who take the reins (at the bit) and help me with feel. I have also had an unmounted clinician lesson whereby she'll hang the bridle from her head and hold the bit in her hand and close her eyes (facing away from me) and I have to give instructions via the reins; then we swap places and she tries to replicate how I was holding the reins so I can feel what I was doing. I will say that I historically had ridden with a loopy rein - from my hunter days, I suppose - and would "throw away" the contact when we were cruising along in neutral. But that doesn't keep a constant communication with the bit, and it is actually quite surprising (in my hand when I was holding the bit) to have no contact and then some contact and then no contact and then some contact; as the horse, I wasn't ready for the next signal because the rider had to pick up contact before giving me an instruction and it was very confusing. That was an eye-opening lesson for me.
Yes, absolutely I use one rein at a time, or both, or one more than the other, or sometimes strongly to get the point across, or whatever my horse needs at the moment. I guess I don't have a "one technique fits all" approach. I'll do what my horse needs so I can get my message to him . . . I find it is a constant conversation that is only "silent" when we're on a break and moseying around the arena.
As a yoga teacher for riders, I've also done lessons in my class to work on feel and soft, moving elbows. Use a lead rope or yoga strap or bathrobe belt/tie . . . something long enough that you can wrap it around your feet and have the ends be "reins." Sit on the floor with your legs straight out in front of you and your body upright (you might need to put a pillow under your bum if this strains your back). Wrap the middle of the strap around the balls of your feet and take the ends of the strap in each hand like reins. Sitting up straight, move your feet in a pointing-and-flexing manner (but you might not point all the way because you don't want the strap to fall off) - just enough to create movement that you'll need to follow with your hands. Close your eyes and notice what you feel in your body. What does your usual contact feel like to you? How light can you go with your contact and not have the strap fall off? Where do you notice any blockages - shoulders? Elbows? Wrists? Are your hands relaxed? Are you breathing? There are all sorts of things to be aware of in this simple exercise.
I strive to be a better rider with my balance and position - sometimes I really have great moments where I feel at one with my horse and we are totally in synch and I feel like "that's IT!" It is those moments that I keep trying for, working on myself and what I can do to get there.
but remember the western riders goal is to ride with no contact, of the slack rein, so see sawing is to get the horse behind the bit, basically. This does not translate well to dressage and is a "set position". It came from ( i believe) the baucher protege ( whose name escapes me) who came west to train the american cavalry. You also see a mutant of baucher flexions used often in western riding)
When I first started riding I was taught to see-saw. I have video proof! And I rode completely off my hands. When I got my first horse, she had a serious opinion about that. Things went down hill quickly and our rides got so bad that I cried after every ride. I was lucky though. A new trainer moved into the barn and took over. She took the reins away from me and put me on a lunge line. I learned to ride through my seat and legs. I also learned how to ride with independent aids. She taught me how to train green beans and refine the aids on any horse. And I have to thank for the rider I am today. Although she never did get me to keep my fingers closed. LOL
Right now there is a girl that just moved into the barn. Horse is super duper cute. Nice mover and I literally watched her see-saw his mouth to try to get his head down. He goes around like a giraffe. She has a "trainer" and the bad habits get worse from there. Not the girl's fault, she doesn't know any better. But she did ask my advice about something, and I flat out told her that her horse is not a piece of wood, so stop sawing on his mouth. Not sure it did any good. My point being, there are still these useless trainers out there teaching this garbage. And I hope for her and her horses sake she gets a to learn with someone wonderful like I did.
My coach is always saying how when you're riding, the body is basically divided into three parts - the upper body, the seat, and the legs. Your hands are in the "seat" category. A good hand does not work without an effective seat. Each part is important, and each works together - but the hand and seat are part of the same group.
I have had instructors who advocated "ripping their heads off" if they got strong. Not a nice way to teach soft hands. Or, indeed, anything about seat. Or riding in general. Thankfully, I wasn't with them long, and have gone on to have MUCH better instruction both before that short period, and after.
I don't know if feel can be really taught with a person holding the other end of the reins as, to me, feel isn't just about what the mouth is doing - it's what the rest of the body does that you also have to be paying attention to. You need to be able to feel when the horse gives you its body, when it takes that stride that is just that much softer, more supple, more engaged than the last. THAT is all part of feel - which ties right back in to the first paragraph of this reply, where seat and hand are connected. Feel can't come just from hands alone.
I like whoever said the contact should be alive. That's a good way of looking at it! The contact doesn't necessarily remain the same all the time. Sometimes you need to take more, sometimes you need to give, but you do need to maintain a feeling hand - not taking the rein, and not throwing it at the horse, either.
Another thing my coach says is "be positive, not passive". Definitely something that applies to hands and contact. A positive hand is not a pulling hand, nor is it an absent hand.