What you are training
Every section of a song has a job. The verse delivers new information and moves the story; the pre-chorus builds tension and points at the title; the chorus states the idea and stays put; the bridge changes the angle. When a section is doing the wrong job the song feels long or confusing, and the writer often cannot say why. Naming sections quickly, from the lyric and the music together, is the foundation of every structural decision. This drill plays or shows a section and asks what it is and what it is doing. The reveal names the tells: harmonic rhythm, lyric density, where the title sits, whether the melody resolves. A few rounds are enough to see why the most common pop form works and where a song of your own might be carrying a verse that thinks it is a chorus.
After this drill, the plan: The daily plan moves from naming sections to building them: the song form builder, then a pre-chorus you write for one of your own verses.