Great job so far everybody! Again, please see as many videos of others as possible and read my comments to others too - I'm trying to bold the answers you really want to read, but the more you read, the easier it will be to understand what you're going for.
But things are mostly going well now, the only problem that I'm seeing more as expected is "up-in-the-air" movement. It looks like some dogs are leaping in order to get away from the plank. I think it's mostly due to the fact that everybody is going for those narrow planks and those are hard to run full speed on + they might sometimes be stepping on the edge and that can be uncomfortable and make them want to leave it as soon as possible. So again - it's no hurry to get to a narrow plank!!! If you can use two, side by side, with a carpet over, that would be perfect!
Anyway, here is your new list:
1. gradually make that plank higher&higher, still jackpotting the best hits, but make a criteria for a jackpot somewhat more strict and at this point also already stop clicking the highest hits even if the dog is striding equally - but at this point, don't click anymore the highest 20% of the hits you're getting (meaning that from 10 tries, don't click the highest 2 hits). It's no problem if the dog still gets the toy, just take it immediately when he comes back. When it's good, praise and tug and when it's especially good, be especially excited and play especially enthusiastically 🙂 And yes, dogs are smart enough to know the difference.
2. as the dog is probably already searching for the plank better, slowly start throwing sooner&sooner. Don't rush it, but you eventually want to throw that soon that the dog is technically running to a static toy. But again, you don't want to get there sooner as in 3 weeks as it's only then that we'll start using a static toy - you do want to throw it for those 3 weeks more! It's better to throw somewhat longer if necessary - usually not an issue with BCs, but with my puppy, I needed to throw VERY long to keep the speed and focus - if any of that gets weaker when you start throwing sooner, go back to whatever gives you back the speed and forward focus, we can deal with that later!
3. as you are still throwing a toy, your movement and position probably won't affect the dog's performance - but just to be sure, do try to run with the dog here and there, just to check if that's correct. If it does affect your dog's performance, add movement gradually, by first walking slowly along, then walking faster, running slowly etc. You don't need to do it on every try, especially not if it doesn't affect the performance, but do try it here and there.
4. another difficulty we can slowly start introducing now is changing starting position of your dog. Don't use the best spot all the time anymore, but vary it a little bit. If it makes their hits too bad, go back to the good starting position. But bad hit here and there is good, that's how they learn the difference between what gets rewarded and what doesn't.
5. new trick: shape a dog to go with all 4 feet in a box that is ideally as long as he is. Then gradually use smaller&smaller objects, your goal is the dog is standing with 4 feet in a small bowl. Good for balance and rear legs awareness! Also, teach backing up with you standing still, by throwing a reward for them first for one step back, then two and then add more&more distance. Great for rear legs awareness and coordination!
Send videos of the tricks and the plank work. For slow motion part of a plank work, PLEASE cut out all the parts where I can't see the dog! It's very time consuming and not much fun to watch just the plank or you, throwing a ball, in slow motion!
Also, here is a video showing different striding on a dog-walk. My puppy Le is showing the most common striding: two hits on up plank, two in the middle, two on down. Bu has this same striding. Bi can only do that if I start her from such an angle that she has no speed coming up. Her normal striding is 4 steps on whole dog-walk, on down ramp rear feet hit first and then she lands front feet above the contact, hind feet in the middle. I think that since US dog-walks are significantly shorter as mine, many of your BCs might end with this striding. Bi usually does shorter dog-walks in 3 steps (our dog-walks come in different lengths) - you can see one of those tries in this video too. She is pretty high on my dog-walk, but comes deeply in in 3 strides on shorter ones. At the end, you can see what big area she is covering with one hit, thanks to good reach forward and hind feet separation - with one hit, she is touching almost 40% of a down ramp, that's 1,5m!