With that I tried to find out more for myself. I bought a pair of Dr.Denim Harris Blue Black Raw jeans and put the theory to test, that you should wear your raw denim jeans for a long time before washing them. According to Dr.Denim, you have to break them in first. Here's how they describe the process. "Before sanforizing (pre-shrinking of fabric) was invented, cowboys used to jump into the lake wearing their new jeans and let them dry on their bodies to get the fit right, before wearing them day in and day out. Fortunately, pre-shrinking keeps you dry. Just wear the jeans for a long time before you wash them, It makes them look better, last longer, and it's true to the good old way of doing things. It'll be a smelly story but the end result should make it worthwhile."
The reason why it's generally recommended to wear unwashed denim for a long period of time is that there is a lot of excess indigo dye stuff on the yarn in the unwashed state, making it easier to obtain natural contrasts from wear and tear. After one to two years of heavy use, you should get something that looks a bit like this.
