Getting an inside bend with the inside rein can be an end in itself meaning there is no corresponding outside rein. I've done this with Speedy plenty as we school the shoulder in. Sometimes, he simply refuses to let go of (or soften) to the inside left rein, so I will drop the outside rein completely, and over bend him to the inside while driving him forward down the long side until he gives to that rein.
For the last few weeks I've done something similar with Izzy. I've bent him to the inside as we spiraled down to a smaller and smaller circle until he made the circle without any tension on the inside rein.
It's a subtle mental shift to leave the inside rein alone in order to focus on the outside rein. My job is now to be very firm and supportive with that outside rein without letting Izzy drift out or be counter bent. This is where my seat and legs come into play. If I use too much inside leg, I will push him out so it's important to keep my outside leg and rein there to say not out this door.
A few moments after that discussion, he launched straight forward into a huge bolt. Again, that wasn't the right answer, but at least he went forward instead of up. And again, I know that he was just trying to figure out the easiest way, meaning least amount of work, to do what I was asking.
After getting told quite sternly that rearing up and bolting forward were not the correct choices, he finally got the answer right. There was still a fair amount of tension in his neck, but by using Chemaine's strategy of compressing his stride with the outside rein and asking him to soften to it with the inside leg really started working.
I held that outside rein firmly until he gave, and then I softened and asked for a slightly bigger stride. We did it over and over down the long sides, across the diagonal, and while doing 20-meter circles. While this softening exercise is about getting more throughness at the trot, the effects can also be seen in the canter. Izzy can now pick up the canter both directions without exploding. Mostly.