I inked in images for the letter D the other day. I figured out it takes about a day and a half to finish one page. About 4-6 hours to compile a list of things to draw from, then about 10 hours to research and draw, and then about 6 hours to ink. I mostly reference google image, and I compile my list using Marci's mini-dictionary, crosswords reference websites, and an Audubon Nature Encylopedia. I try not having to many animals or plants in each drawing, cause you know, a diamondback is really just a snake, and a discus is really just a fish.
Fun things to draw: Donuts. A dozen of the one I remember. Dog in a duffle bag.
I also drew a devil drinking a cup of tea.