The simplest way I’ve found of working on this is a single small fence on the centre line of the arena. The (yellow) plank is an optional extra, very good for making sure you’ve got the right SJ canter, and for practising flying changes over.
The upright is deliberately small, and the angled pole underneath is something I picked up from a trainer years ago. It makes the rider stick to the middle of the fence and not allow the horse to drift, and it makes horses pay a bit more attention to a tiny fence, since it is a little bit of an optical illusion. I wouldn’t do it for a big fence but for something like this, below 1’6″ high, I think it’s fine.
As you circle over the small fence, just looking further around the circle and opening your inside rein slightly should be enough to tell the horse which leg you want him or her to land on. When you’ve got it right a few times, change to doing a figure of 8 with the jump in the middle, so landing on the other leg. Then change between the two patterns, circle or figure of 8. You can have lots of fun, work on your position, keeping a good rhythm to the fence, seeing the right spot, making sure you follow with the hand and allow a bascule, even to just one small fence.
You can play with the number of strides you can see to the fence on the turn – on a 20m circle I’d expect to be seeing 4 or 5 strides.
You can also play with coming to the fence on more of an angle or not, and turning in the air slightly or landing straight then turning.
Landing on the correct lead is a huge deal in the SJ, making rounds look so much smoother and more professional, saving time and saving having poles down. This is definitely homework worth doing!