I hear people talking about why quads are so important, but why?
from: Subdivision Modeling page: (an oldy but a goody.)
While most modeling packages allow you to model with faces of virtually any size, if you intend to smooth your model, your results will be more consistent and predictable if you stick with quads. This is because bicubic smoothing works by averaging the tension between the corners of a face. In this case, a quad has a consistent “center” that you can clearly visualize by drawing an x connecting its opposite corners. Non-quads don’t have such an obvious, predictable and even distribution of tension. Unlike quads, there’s no guarantee a non-quad’s center of tension will coincide with its center of volume. And this, as you may have already experienced, will result in pinching when you smooth.
It’s particularly important to watch out for triangles and have strategies for dealing with them. It’s very easy to introduce triangles when you’re building edge loops. A particularly common scenario involves crossing the corner of a quad:
Ok, thanks. So is that why when I try out my model in a game some of the faces don’t show?