[bingoguitars]

true it does depend on the style they were going for. But all I was attempting to say is that if the drummer just practiced with a metronome, when the songs are recorded things will stay together better. He or she could eventually feel if the tempo was racing or breaking. And that all in all would make for a tighter more mature sounding band. They are not playing punk rock. Metal (depending on the era) is much more composed and intricate. I was not trying to say that they were so off I couldn't enjoy the music.
Bottom line is different strokes for different folks. If you like the unrefined/sloppy/raw/organic sound where the tempo moves around then keep it.
If your going for that ultra tight/robotic speed/staccato/intricate sound just give the metronome a shot for 1 month and see what comes of it.
and wasn't the metronome invented in the late 1700's?