REQUEST:
Having 3 kind of pre-define Pencils, each one with a FIX specific colour as a default (unless the Black-Pencil-Tool which is the main Pencil Tool) will help animation with a faster work flow.
One pencil with FIX colour RED (for making BACKGROUNDS)
Another pencil with FIX colour BLUE (for making the rough draws and in-betweens)
The last pencil with CHANGEABLE colour would be (as a starting point) BLACK (for cleaning and finishing)