All these were completed in the same day I started them, render them out using the same composite node setup to make a multiply map consisting of the AO pass, shadow pass, and brightness values of the image itself, and stylize or fix something in the image in post-pro. It does help if you start working on them with a clear vision of what you want to do and quick know just how you’re going to do the materials and the models.
The only exception is the space one which I completed and then the next day decided I had to fix a darker curved line in the background in a paint program. Just to show that I still use Blender frequently on occasions if you’re one of those who think I don’t do much with it. This using Kai’s build (but not using the GI or other features not in SVN)