Ah, the irony - the entire point of this form of teaching was to ensure that Yamatsu would come out of this lesson having learned the jutsu properly and being able to use it without even having to think about it. Yet, in order to defeat the opponent, he had learned one of the most important techniques - How NOT to use the technique.
An old phrase popped into Sho's mind as he watched the debacle in front of him take place, an old bit of folk wisdom about how jazz was about all the notes you didn't play.
Either way, Yamatsu launched forwards the same technique that he had done before, and there was a moment where the clone could have shunshin'd away. If it had wanted to, it could have either dodged, or continue moving through the flames. But there was no point at this point, the lesson had already been learned and it was transparently clear that this level of training was over.
As such, Shosuke let the technique drop, desummoning the clone. In the moment that he did so, rather than the clone dissipating into smoke as a shadow clone might, it almost looked like a puppet without its strings collapsing to the floor, lit up and smoking before it fell down into the water. For just the briefest moment, the air was filled with pungent smoke like that from a bonfire, before the body plunged beneath the waves, falling apart into flotsam that was pushed away by the current of the technique.
Sho, for his part, simply let the other jutsu drop, the water coming to a trickle and then a complete stop. The only problem with this technique was that even once Sho was done with it, the water in the training area didn't go anywhere. It would take some time to drain down the mountain, forming a muddy trail in its wake, but fortunately the current shouldn't be strong enough to dislodge or do any damage to anything beyond the training ground.
"Well done, kid." Sho's face was one of genuine warmth and pride. Despite barely knowing the kid, it was good to see them actually learn the lesson. Some might say that he cheated since he didn't use the technique to win the fight, but this was informal training - there was no cheating, as long as everything that needed to be learned was learned that was all.
"Tell you what - let's go get some lunch. You just used up a decent amount of chakra, you need to be well-fed if you're going to recover properly and I don't want your master getting mad at me for making his student useless for the rest of the day." 
