Such an amazing scene, maybe my favorite part in the whole film. Glad to finally find out who animated it…

I remember reading that animators working on the film didn't understand what he was doing when they saw him working on the animation. Nobody could quite grasp why he was bothering creating drawing upon detailed drawing that to casual eyes looked almost identical. It was only when they saw the finished product that they realized the impact he had been striving to achieve with those painstaking drawings. He had set out to raise the film's bar of realism, and worked patiently to achieve that effect despite the incomprehension of his co-workers.
from :
(http://www.pelleas.net/aniTOP/index.php/toshiaki_hontani_a_26412_a_35895_a_21033_26126 )

https://twitter.com/osamukoba/status/1123956449418334209

他の田中くんマッドにアキラカプセルが割れるとこ出てきたけど、あそこは本谷さん。

Tatsuyuki Tanaka did character part in this scene.

source: http://www.style.fm/as/01_talk/tanaka01.shtml
animator interview 田中達之（１）

最終パートに参加する事になったんですけど、その絵コンテは、まだできていなかったので、しばらくはこぼれたような部分の原画を担当していました。本谷さんのパートの合間合間に入る大佐やドクターが驚いている顔のカットとか、ケイがスパークしながら弾かれて飛んでいくところとか。あれがいちばん最初に描いた原画じゃないですかね。

Does anyone know who decides which cuts are made in 1s?
I don't think it's the animator's own decision, is it?

@grardox I have no idea and I’m just guessing but I would imagine that the director would tell the animator what they want the scene to feel like and the animator would have to figure out how to achieve that and that could include choosing to do the scene on 1s or 2s. I think they might also have to consider budget since working in 2s means double the work. Also each team is going to have different pipelines so it’s hard to figure out a single answer but I would say the animator is probably making this decision most of the time.