I'm a big fan of loose rein cantering - with a horse that knows how to canter under saddle, and has some relaxation plus forward built in through foundational softening work at the walk and trot, it can be a great way to help the horse develop balance and self-carriage.
Red had a day off today - a friend and I went out to lunch with another friend, who is 95 (has a little trouble getting around but is otherwise sharp as a tack) and living in a retirement community nearby - so I was short of time. Red and I did some "just standing around" work in the arena - he and I both find this very relaxing and useful - for a horse who used to fidget and couldn't stand still or notice I was there, he's come a very long way. We just stand there together, breathing together, and it is very fine.
This morning, Dawn and I did some very nice loose rein canter work, and Pie and I did some more in the afternoon. It's a great test - will the horse maintain a balanced, relaxed, forward - energy but no rushing - rhythmic canter without your interference? Will the horse track into the corners, or cut them? Will the horse maintain/sustain the canter or break to trot before you ask? All of these things will reflect the quality and consistency of the foundational work and how you are sitting and riding. And you can't rely on your hands to fix things - they have to be right in and of themselves.
Both Dawn and Pie did exceptionally well. Pie and I have also just started on walk/canter transitions, and he's already very close to having them - but it depends on me mentally preparing for canter - thinking the rhythm - to the point that all I have to do for him to strike off is exhale. He's getting the idea, and I think it'll come together pretty quickly.
Good horses all around - I am very blessed.