A whole lot of people not that into horsemanship but into horses don't understand that feeding them, leading them in and out of the fields, that's where horsemanship lies. Or doesn't. Riding, that's a thing, sure. A really really big thing. But if you are riding a horse you can't actually lead, well, you are riding some pretty big holes.
If you can't lead a horse through grass and not have that horse dive to pick grass, your timing is bad. If the horse makes it to grass, he has his reward, and you are likely pulling, jerking, yelling, hitting --or saying, well, ok, have a bite or two, that's fine.
That's what "do less sooner" means. You have to be paying enough attention to know that horse is about to go for grass before much, if anything, visible happens. Then your response can be a very very very light "pay attention" change.
If the horse pulls before you even know it is happening, you are going to have a pulling horse, and never ever ever lightness.