Well, you can use a clicker or not. But what is important to me when training anything is that the dog is given the optimum odds for succeeding. The more reinforcers the dog gets for correct responses, the better he learns. If anything is rushed or done in a way which is difficult for the dog to understand or too much to handle, he's more apt to break the stay and when that happens, he just lost out on a chance of a "win." He should never be corrected at all for something he hasn't learned. Sometimes we think they know something, but they don't know it well enough. Why would a dog screw up on purpose when he knows he'll get a wonderful reward for doing it right?
Personally, I avoid using any force or creating a physical impossibility for him to break the stay. I like him to figure it out on his own....what gets him the reward and what doesn't. It makes the dog use his noggin a little bit more. Make sure you have something he really really loves....a hungry tummy helps.
That said, how I train stay is to break it into three parts because there
are three parts. LOL. There is the
duration the dog will be asked to stay. There is the
distance from the handler and there are
distractions. I do not ask the dog to think about or to do all those things at once...too complex. And higher odds that he'll screw up. I want the dog to get tons of reinforcements, and the goal is NO mistakes, so I keep the goals small at first. (Any time there is a skill which has different facets to it, or can be broken down..... and most things do, try breaking it into parts and concentrate on one part at a time)
So, I start out with duration (only) by putting the dog in a sit and standing right in front of him, facing him. (body language of facing him, slightly bent over will also help to inhibit his moving forward) I sweep by hand or just palm facing him close to his face for a sec. I don't even use a cue word at first. I click/treat for one second of staying. (or if you don't use a clicker, praise/treat) Then get up and walk around in a circle to start over, put in a sit and repeat. If he was able to stay for 1 second, try 2 seconds, then 4 seconds.
Reward every single time. Don't rush. You don't want him to mess up if you can help it. If he can't hold it, you've gone for too long. When he is obviously understanding that he's to stay put, start adding a cue word, "stay." Gradually lengthen the duration. Continue standing right in front of him. When he's getting good at holding it for a while....like 10-20 seconds...is really seeming to catch on, you can start working on distance.
Now, put him in the sit/stay. I continue standing in front of him, facing him, bent a little. (later you can practice walking off from his side) In the beginning that may cause him to follow you...that's why I bend toward and over him just a tad and step backward a step. I'll take one step back and immediately return. Forget the duration for now. You'll get back to that later. You can click/treat when you step back to him, but remember to use a release word. In other words, just because you reward him doesn't mean he gets to get up yet. Then try 2 feet away and immediately return. Don't even pause at all. Then 3 feet, 5 ft....something like that. The more times he "wins"....gets reinforced, the better. Don't go too far too soon and come back immediately, like you're attached to an elastic band. After you're able to get 6 feet away and he's staying, start adding the two together (duration and distance) Step away a foot and try to have him stay for a few counts, then a little more distance, a little longer....just gradually. Don't forget lots of treats....every time he succeeds. If he messes up and breaks the stay, he is not being stubborn or naughty. He just needs more reinforcements. That's what makes dogs repeat a behavior....nothing more, nothing less.
Then when he's getting really good, start adding a little distraction, a little more next time or as he's able to do it with the previous amount of distraction. Again...if he messes up, he's not being "disobedient." He does not need a correction. He's not ready for that much distraction or he's not ready for such a long stay or so much distance between you. Go back to where he was successful and work there for a while longer and then creep up gradually again. Also, changing locations is good. He may have trouble at first with a new location. It's different to him. They're not good at generalizing. So, just go slowly. So what seems normal and logical to us is not always the way they see it. Your dog is guessing at what you mean. It takes many reinforcements, many reptitions with lots of reward to make it so he goes from the guessing stage to the sure of it stage. LOL.
Hope that helps. If you use a clicker and the stays are getting longer, you can click, (as long as your dog knows a release word and doesn't get up) and then return promptly to give him the treat. Or just walk back and c/t. Never ever click without treating right away, even if you click an unwanted behavior by accident or if it goes off by itself. LOL.
A clicker is very useful when marking a specific, precise behavior, something that hapapens more or less instantly. Like teaching a dog to sit. The instant his rear hits the ground, you c/t. He knows that that movement or position is what you wanted. With a behavior that has duration, you can c/t and let the dog know he's on the right track but it's not as beneficial as with a behavior which only takes a second or two. If you want your dog to continue staying (but it's not the
long stay) the clicker, I think can be a little disruptive. I prefer to use the keep on going signal. But if you go
gradually enough and break this into parts, you will find that you won't need to do much of that intermittent fuss at all. You'll be rewarding frequently enough because you're causing successes every few seconds.
There is also a
keep on going signal. You can use a word, the same one which lets him know that what he is engaging in (ie: the staying) is right on track. I sometimes will use, "good, good, good" in a sort of quiet, cautious tone with a little inflection at the end. That is useful with behaviors which are sort of long lasting, like a stay.
I have used a clicker with heeling to get the heel more tidy. I just c/t often, every few steps (it's easy because the dog is right there) which were just right and not for the lagging or forging steps. Don't let a habit develop of the dog getting up or breaking whatever he's doing just because you praise or reward him. So, keep the praise low key if he's apt to do that. Work on a solid release word too and replace him in whatever he was doing if he breaks it before you say, "ok" or whatever your word is.
As the stay gets better, distance and duration....like when I'm working on a
long down/stay, I'll return to the dog and pop him a treat quietly, no fuss and walk back again. In other words, he is not released. He is to continue staying. (I might even re-do the hand signal to remind him) I'll do this rather frequently. It encourages him to stay put even if it's really boring. It also helps reiterate that just because he's getting rewarded, it doesn't mean he done yet. Then I'll space the treats out later until he no longer needs them until the very end of the exercise. But with this, remember, it's still important to make it so the dog will succeed (lots of reward)....gradually longer distance and duration.
Another tip....don't be in a hurry to call your dog to come from a sit/stay or a down/stay. Always return to him for a long, long time....months. You want that stay
really solid with little chance of him anticipating your calling him and him breaking it. Only after it's rock solid do you start doing the recall from the stay.
As an aside: I think a lot of people skimp on the frequency of rewards. Set the dog up so he can get rewarded often. Like with pulling on a leash or getting the dog to heel, the dog will take 2 or 3 good steps and he doesn't get reinforced because the owner is expecting him to walk all the way to the end of the block nicely. If the dog takes 1 or 2 steps nicely, reward. How else is he to know that what he's doing is what will earn him what he LOVES. The more of those wins, the quicker he'll learn. He's going to choose the good stuff as long as he understands. That is why I disagree with corrections.
If the motivator and reward is something the dog is crazy about, he's going to choose what gets him that as long as he knows what he's suppose to do. He's guessing for a long time.
Hope that makes sense. It's long enough. It better.