By themselves these two observations don't really mean much, but taken together they create a lot of potential for interesting roof design using what I have called roof stacking. There are two general ways to go about this technique. The first is to just overlap sections of roofing that differ only in pitch. Looking at the first image below you can see what I mean. Here I took two roof sections, one with a shallow pitch (first small house) and one with a steep pitch (second small house), and overlapped them on the third small house found on the far right. This creates what is called a bell-cast shape to the roof by adding a small flare on the bottom edge. The exact steps I took were to place one roof piece, lower the pitch with the roof section pitch control, and then place the second, which was at default pitch.
With the next image, you can see how I've used this idea on a custom bay window (I forgot the windows so you'll just have to use your imagination). I've seen this type of roof design on bay windows found on many traditional styled homes. It's a nice way to make a bay window more interesting and more closely resemble those found in real life. You might have noticed that this technique does create a thicker horizontal band on the bottom edge of the roof, which is called the fascia. You can see it's doubled in size in the below image so if ever a build calls for thick fascia then there you go. Haven't you ever just thought that a sim house would look better with a thicker fascia?...what, you're not that strange...well I have.
This last example doesn't exactly follow the technique I described, but I didn't feel like devoting an entire blog post to it so I included it here. It is, however, an example of overlapping roof sections so it's appearance here is not due entirely to laziness. As you can see below, I've created an elongated domed roof by simply placing a long line of domes bunched tightly together. Right below that image, you can see how I incorporated this design into my Waddesdon Manor. The real design uses a convex mansard design, but that is, as far as I can tell, impossible to do, so this is close enough.