Yep. YOu can use the toe in the chin if you want, but that only works when you are right next to them.
I lead my horses off of me a bit, and when I go through a gate or somehting, while I am chaining it closed again, they must stand and wait. They sometimes get to thinking that the grass looks good. I watch 'em out of the corner of my eye, and if I see them even THINKING about the grass, I interrrupt that pronto. I can use as little as a verbal hiss or an "ah! Ah!", or, I can use the lead line and by swinging it back and forth I send energy down the line until it bops up agains their jaw. I dont' stop until they lift their head. Once you've done that a few times, and use a verbal scolding sound, then you dont' have to use more than the scolding sound.
However, I encourage you to look at it as something that you must be 100% clear on. So, no hand grazing with the horse on the lead line and you holding it. You can't have it ok sometimes and not ok others. When the horse is on the leadline in my hand, there is NO grazing. If I must let him eat, then I drop the lead line on the ground.
That's how I do it. It's just one way that works, not THE way.