Sometimes when you are recording a new track it is good to turn off the metronome and auto-quantize using your software, just hit record, and play from the heart. A spontaneity and more human quality can be captured in the performance. This works particularly well with solo guitar or piano.
Or maybe you want to use some audio from a live recording or a studio session where no click track was used. When it comes to adding other sequenced parts to audio that has been recorded in this way it can be difficult to get the timing of the midi notes right. The metronome and auto-quantize will be out of sync with the audio.













