A bit on the story structure of Sound! Euphonium 2 episode 12
(There are spoilers here.)
In commentary about Sound! Euphonium 2's episode 12, a number of people have noted that KyoAni took the unusual step (for the show) of not showing Kitauji High School's performance at the Nationals. Instead of seeing any of their performance, we cut straight from going on stage just before the commercial break to the after performance wind-down after the commercial break. Nick Creamer's episode writeup at ANN is typical, and he says:
And then it was over. Sound! Euphonium's final performance, the nationals performance that this whole season had been leading up to, took place entirely during the episode's commercial break. I had to laugh at that - after all of this work, after performance sequences as stunning as last season's conclusion and this season's halfway point, it felt like an intentional flaunting of expectations to actually cut this one out.
In my opinion there's a very good reason that KyoAni did not include the performance and it has nothing to do with flaunting our expectations and everything to do with story structure (and a bit to do with how stunning those past performances have been). You see, this time around Kitauji lost. And not because anyone screwed anything up, as far as we're told; everyone played their best, it's just that at the level of the Nationals, their best was only bronze level.
In the two previous performances that Sound! Euphonium showed, Kitauji won; they took gold and moved onward towards the Nationals. Portraying this in a show is theoretically simple, as all you need to do is show everyone playing well. We the audience will read into the combination of a dynamic, well-done performance that sounds good and Kitauji taking the gold the implication that Kitauji had the best performance, without the show actually having to show this explicitly by, saying showing another, not as good performance by another high school.
All of this goes out of the window when Kitauji's performance is only good enough for a bronze. How do you portray a performance that is good but only so good, especially when you've shown Kitauji playing very well before? If you just show Kitauji's performance (and at their previous level), the audience is unlikely to be convinced that they only deserved bronze. So to really sell this you would probably have to show at least parts from both Kitauji's performance and a clearly better performance (ideally one that only got silver). That is a tall order both simply for time in the episode and also for showing relative performance level, especially when Kitauji is supposed to be good to start with.
(The one time Sound! Euphonium did a compare and contrast performance it had the significant advantage that one of the people involved was clearly not all that great at her solo. Portraying 'good, without errors' and then 'clearly better' for orchestral music is likely to be hard, especially if you want it to be unmistakable to the audience.)
Given all this I'm unsurprised that KyoAni skipped completely over the actual performance. There just wasn't any good way to portray it, at least not without a lot of work and risk of audience (dis)belief in the outcome. Skipping it was almost forced by the structure of the story. As much as we might have liked to see it, it would have been hard for the show to not let us down if we actually got the performance.
(And this way the show could preserve tension that held through to the revelation of the results. If the show had convincingly told us that Kitauji's performance was below the level of other bands at the Nationals, we'd have known they weren't getting gold well before the results were announced.)
(This elaborates on some tweets of mine, because I felt compelled to make my logic explicit.)
PS: To be clear, I don't fault KyoAni for this decision or think that it weakens the episode. On the contrary, I think it's a clever solution for a real problem, one that has significant advantages and helps the overall story of the episode.