as with any discipline you need to learn to ride in it to do it properly, but if you are buying a horse that is already solid in their gaits -really you just need to learn to correct them when they go out of gait and learn what it feels like when they do -same as you would learn to round a horse when they get strung out in dressage.
My horses, and all of our horses on the farm gait in the pasture naturally, but when they go out theyre all different, and all gaited horses go out sometimes. My gelding he does a hard pace when he goes out -he doesnt do it often but when he does i just ask him to move off the rear, and he regroups. You dont want to ride that pace lol. My mare, again doesnt go out often as she has been consistently ridden and trained -but when she does go out or when she was just under saddle at 3 yrs old, she tended to go to a step pace, which is actually quite smooth and if you're looking for a good trail horse one that does that as their 'lazy gait' is quite pleasurable to ride. It's all what youre looking for.
All of our horses are barefoot or keg shod trained so you dont need any devices to make them walk, they were bred properly and there are some of them out there.