There's no reason at all you can't put 10 horses on six, open acres assuming the acres are reasonably flat. There is more than enough room for the herd to set up their own "pecking order." If you're in NV you'll have a different feed program than if you're in KY, but that's about all.
Riding style has a tremendous impact on gait. So does saddle placement, bit placement, stirrup placement, seat style, equipment used, etc. If all you want to do is "piddle" on a horse then ride as you will. You'll find, however, that proper equitation means lower vet bills and a healthier and happier horse.
As you might guess, I'm not a "natural horseman."
Over the years I've learned that domestic animals require handling or they move toward being feral and that's a problem. I've seen a ton of injuries to horses and humans resulting from humans not adequately keeping their horses "domesticated."
Everybody gets to do with their horses what they will. But every action, or non-action, carries consequences.