What you are training
Attack and release decide what a compressor does to the shape of a sound, and they matter more than ratio. A fast attack clamps the transient and makes a drum feel further away; a slow attack lets the hit through and compresses the ring behind it, which is how you make a snare punch harder. Release decides whether the compressor breathes with the music or pumps against it. This drill applies a compressor with a hidden setting and asks you to identify it: fast or slow attack, fast or slow release, light or heavy ratio. You hear the same phrase under each choice, so the contrast becomes a memory you can reach for at the console. Eight rounds is enough to learn that attack is the setting you can hear most clearly, and that most presets have it wrong for drums.
After this drill, the plan: The daily plan drills attack time on drums and vocals separately, because the right setting is opposite on each and presets ignore that.