My daughter's 11 year old QH mare seems to be very fickle with her bits. She likes a cheap o-ring snaffle--for awhile, but then she starts to ignore it. She likes a Myler mild correction bit (level 1-2) for a while, but then starts to get pissy because it has more bite. (By pissy I mean very tail swishy, tossing her head around, but she doesn't ignore it.) She also likes a smooth Jr. Cow horse bit, again, for a while, then sort of does a combo of the other two. Right now my daughter mixes it up. One ride, uses a snaffle, then rides her in the Myler a few times, then switches to the cow horse bit and sort of does a rotation. When she's doing cow work or barrel racing she specifically uses the cow horse bit, when she's doing 4-H performance/reining, she uses the Myler because 4-H requires a curb. When she's playing around on the trail course or on a trail ride she rides in the snaffle.
Is it normal for a horse to be this fickle? Are we screwing things up by switching on and off? Truth be told, when we regularly switch it up, she listens to all of them better. Right now we're borrowing the Jr. Cowhorse bit and that seems to be her favorite, but I need to double check to see if she can use it for 4-H fair in 3 weeks. In my experience each horse I've ever ridden has a "favorite" bit and that's what the do best in. I know that people try a lot before finding one that really works, but it seems like if you use the same bit on her for too long, you get a snotty horse, but mixing it up keeps her happy.