Literally little Photoshop comps.
Done tiny - these cant have much detail. They have to be about the layout.
Oddly - no tool I have is as easy to use for fast comping as Photoshop. The program gets this level of job done without the strange hinderances that other programs throw into the process.
Just the brush and layers.
Colors for comping - dropped back so far they (hopefully) dont influence actual color design of the final art.
Probably should have dropped it to grey scale - but no color is no fun.