I usually work on about 18 pages a chapter, sometimes a little more. If I wanted, I could definitely get it done in a week. I couldn't promise quality assurance but I have the time to put my attention into my work. Usually though, it takes about 2 weeks, again, give or take a little.
I can basically get a page done a day but what I usually do is get about 3 pages outlined every 3 day and then get them shaded, toned, etc. the next day. It really all depends on how much I have to outlined because the actual shading and what not is easy.
However, with the holiday season in tow, I've been busy with a lot of things so I usually only get a page or two done in a week.