I was trying out some charcoal brushes on Photoshop to loosen up a bit on my drawing style. Usually I use clean lines and vibrant colors which sometimes can make it quite difficult to just sit back and enjoy the image you are drawing.
With using charcoal and just grey scale colors I feel a lot easier. You can leave some mistakes or unclean lines and it will just look like a natural part of an image.
Even animating with charcoal brushes makes the process much easier and quicker.