For a page, I take 3 or 5 days, because I make the story boards and the story. It all depends of the difficulty of the scenes. I use simple 3D (cubes, spheres, and so on...) for the most difficults backgrounds. I can draw them entirely by hand but it make too long time. So the base is in 3D, but the final picture with all the details is hand made. Not very difficult to do... But looonnnggg to do.
For this comics, I had to search informations about Jerusalem for exemple. I draw the temple of Herode, the Golgotha "mountain", and so on. It took a long time too... But well, it was fun !