My circles probably only like twenty or fifteen feet tops, because I had to pull plants to make it from the overgrown arena. She is pretty stiff but i'm working on physically stretching her legs when I pick her hooves and have her step under herself a lot, which she has trouble doing. She's not lame though I know that, stiff probably yeah, since I just got her back into work after having two weeks off from injury, but she's always done the leaning and the corner cutting even when I had her in better shape, so it's not new.
She generally respects the circle, except for just one spot, her friends are also in the pasture right over the fence so she wants to get it over with and go play with them instead I think.
I know she's got issues balancing because she's under muscled and has trouble balancing herself, especially with a rider on her back as she hasn't been ridden consistently from when she was off the track to when I bought her. So we took a break from riding, since she's not confident yet under saddle at anything other than a walk, as she was pushed really quickly by her last owner, and i'm working on ground work again. I've hopped on bareback though and done hill work to strengthen her hind end though every few days.
Wow interesting video, i'll have to try that tomorrow! Thank you both!