PowerPoint by virtue of providing a Content Master and a Title Master has conditioned the world that presentations only need two looks. When I design a template it generally includes 3 to 4 master slides that go beyond the standard two slide system. Here is a recent example:

(1) Theme Graphic
This slide is used for pre/post-meeting (walk-in/walk-out) or during extended Q&A. Usually with a strong branding image.

(2) Title Slide
Used for introducing major topics, speakers, etc.

(3) Content Slide
Used for all of the content…

– Troy @ TLC