/ic/ - Artwork/Critique

I've seen some artists first do a black and white version of a painting, and then sort of colorize that in order to get a final color illustration.

I think this methodology might help me because it will be probably easier to first learn to get only value right, and then change the saturation and hue on that, than try to get all 3 at the same time right.

I'm curious.
Are there any drawbacks to doing this? I'm guessing it might be more time consuming, but maybe it's not the case.
Are there any advantages, other than the one I mentioned about being able to get one of the three elements right and then being able to focus on the other two (if that even makes sense)?
Also, how is this method called, so that I can find specific tutorials on it?