Paneling — separating out specific still panels like in a comic — appears frequently in anime. Part of this is simply because the source material for many anime comes from manga, and transferring those panels to isolate specific characters from others is an easy visual transition. At other times, it can be used to more clearly show characters’ relationships with each other in an easy-to-digest visual format. Paneling additionally conveys a deliberate thought process especially if panels are revealed in a certain order with precise timing — Masaaki Yuasa’s Ping Pong: The Animation immediately comes to mind.
In Sing “Yesterday” For Me, paneling is used to frame characters’ memories in specific ways that convey their perspective on others or how they subconsciously see other people without them ever saying these thoughts aloud. Panels appear in flashbacks and introductory episode titles, framing how characters think.