Interval-training is a lot more useful. Regardless of what key you're in, particularly if you're not playing (or don't know how to play) from sheet music. E.g.

Interval-training is a lot more useful. Regardless of what key you're in, particularly if you're not playing (or don't know how to play) from sheet music. E.g. given two notes, what is the distance between them in semitones. Once you can recognize any interval then, given a pitch, you can identify the other notes in any chord (major, minor, etc.) it's a part of. Useful for tuning instruments (e.g. guitar). Useful for understanding chord notation (charts), and what chords are being used (progressions). Useful for quickly figuring out all the notes in a melody. (Especially one you want to remember.) Useful for deciding what -scale- is being used (dorian, phrygian, pentatonic, etc.)