He seems to not want to have to look away from the target between shots, but his quiver is placed out of view and he has to look toward it after his fifth arrow. He also subtly repositions his stance after the third arrow. In general, I'm surprised at the amount of motion in his body compared to the stillness you see with say precision rifle or pistol shooters. e.g. 10m air rifle:
https://youtu.be/iTmiMwQnres
Or Olympic archery:
https://youtu.be/fOt4uz-bkfA
Even pool players are extremely still in their motion:
https://youtu.be/-FHz4kf_cus