Just like what I thought.
Based on what I watched from Shirobako, Director draw the initial storyboard with the time line. So, I think all these Neck things & awkward stills are the director fault.
Don't get me wrong, the pacing for this anime is well done, but the animation is quite weird for IG standard (Not as good as Haikyuu).
IG animators rarely messed up the human proportions this bad except for the CLAMP show.