I did Craftsy's Mystery quilt and it ended up being a D9P. I had never done one before so it was new to me. We had to buy a layer cake. We made a 9 patch out of the layer cake. So, it was scrappy. I didn't think I was going to like it, but I really did. I didn't know about placement of certain fabrics, which really didn't matter with a layer cake. I am going to make more D9Ps now that I see how they turn out. I don't have any idea how a D4P works. I guess I'll just have to make one and see how it works. The D9P was fun to make, so I bet the D4P would be, also.