Round pen training works well in conjunction with the Waterhole Rituals after you have developed a well-trained horse at Liberty.
I have found that starting a horse with the Waterhole Rituals instead of starting with a round pen gives the horse more security and a kind of bond that brings out the best performance a horse has to offer.
It takes skill to use a round pen. If you want to use one, I would advise you to educate your horse in the Waterhole Rituals to develop your skill.
If you start in a round pen first, it can put too much pressure on a horse. A round pen keeps a horse the same distance from you giving a horse no relief from your influence. Round pens can initially trouble a horse for this reason—a green person with a troubled horse, not a good idea.
I use round pens for various reasons, but not before Liberty Training, and freestyle dancing with a horse is accomplished. I train a horse at Liberty in a rectangular arena, so the horse has a sense of freedom to lose...