What you are training
A small number of chord progressions carry most popular music, and hearing them is a faster route to writing than reading about them. I-V-vi-IV and its rotations, the minor-start version that turns the same chords melancholy, the I-IV-V of blues and country, the descending patterns behind ballads. Once you can name a progression by ear, you can hear what a song you love is doing, borrow it honestly, and change one chord to make it yours. This drill plays a progression and asks you to name it, in a key you do not need to know. The reveal shows the chords, the function of each, and a few well-known songs that sit on the same four. It is ear training for writers: not theory for its own sake, but the vocabulary to say why a section feels resolved, restless, or sad.
After this drill, the plan: The daily plan moves from naming progressions to building them, then to swapping one chord for a borrowed one and hearing what changes.