We think it take a mixture of:
1) 'wet saddle blankets' or 'miles' -- however you want to describe it
2) Drills and the boring stuff.
If you depend on wet saddle blankets and miles, your horse will learn little other than to go forward and 'guide' a little. Obviously, these are first and foremost on the first few rides, but the horse learns little more. A month off and you only have a horse with the knowledge that the first 3 or 4 rides puts on them plus they are more forward -- often times waaaay more forward.
You must mix in a LOT of jogging and loping circles, lead departures, softening and collecting in the bridle to get a 'slow lope' and a smooth jog and a lot of leg yielding and bending. You need a lot of work on shoulder control or you will never have what we call 'a good handle' on a horse -- I don't care how many cattle you go out and drive or attempt to sort or work. A horse has to be taught to yield to leg pressure; to bend when asked and to stay straight or nearly straight and NOT just bend when you want the shoulders to move.
Miles and wet saddle blankets does not teach any of this. I have gotten on too many ranch horses that had been used on the ranch successfully for years, had drug thousands of calves to the branding fire, pulled off the horn and would load any critter in a trailer miles from the nearest pen. But, they were stiff as a board (Not the same thing as 'straight), galloped with a spine jarring gait (did not know how to slow lope), did not yield to the bit or collect in any way and stopped stiff and hard even when they tried to stop on their hind ends (usually because they had had their head yanked off way too many times). They would go anywhere you pointed their heads, but they beat you to death getting there, were completely 'cold' and unresponsive to the bit and could not slow lope a round circle if their lives depended on it.
To get a really broke horse that is worth riding or worth anything to sell without teaching the boring stuff is like getting a concert pianist without them practicing scales or getting an Olympic Class figure skater without hours of doing the compulsory figures.
Personally, I do not like to teach the 'compulsive figures' in an arena unless the horse has on sliding plates. [If they are wearing sliders, they cannot be ridden in rocks or on dry grass.]
But, I knew every smooth spot in every pasture that did not have gopher or armadillo holes in it;
I knew every clearing on the trail where I could sneak in 5 or 6 circles at a lope before loping on down the trail;
I knew every spot I could lope downhill to help collect a horse;
I knew every tiny place in the hills and on the trails where these boring things can get done to teach the horse how to guide lightly in the bridle and get 'soft' in the face;
A horse needs to learn how to shorten his stride and learn to 'short lope' and slow jog;
He needs to learn pretty collected (head down) a$$ underneath him lead departures in the lead I asked for on a straight line from a walk; [Not 'hop up' in front or 'jump' into a lope.]
He needs to learn to give in the face AND back up lightly and quickly.
All of this needs to be taught to any good ranch / trail horse plus spins, roll-backs and quick moves if the horse is headed toward actual cow work.