Leg yielding is used by nearly every trainer that I have had the fortune to work with or listen to. One or two of the older German trainers have not included it in their training otherwise we will find it commonly practised in walk trot and canter.
Many horses do well if we spend time in walk at the beginning of our work. Walking on each rein on an easy contact so that they can relax.
Parallel leg yields on a circle help to relax the jaw, and leg yields that move towards and away from the centre line, encourage a steady contact on the outside rein.
Understanding how the rein aids work for us is important. The outside rein controls the height of the outer ear, and the inner rein dictates the bend. If you do not maintain the outer rein, you cannot control the bend with your inside rein.
In training, it is the right rein that straightens the horse, and the left rein must supple the horse. To make the horse safer on the rein, lower the neck.
Ride a small circle in the middle of the arena and keeping the bend and circle shape, move sideways and forward to the outer circle, arriving parallel to the original circle.
Ride on the 5 metre line and leg yield back to the track, remembering to travel sideways and forward in a good rhythm. Repeat moving from the 5 metre line towards the centre line always staying parallel. In this exercise you should be able to bend the horse ways.