One of the greatest benefits of working with one lens, apart from being light, is that it solidifies one's creative vision. With a prime lens bolted on my camera I know my photographic limitations before I start out and thus my concentration is focused entirely on capturing images I can take with my chosen focal length. I can recommend using just one lens as a valued discipline. It is something all photographers should experience at least once along their journey. It frees up the creative process and prevents indecision when the viewfinder is at the eye. Remember that there is no opportunity to frame by zooming in or out with a prime, so one must plan their composition before putting the camera to the eye. With a bit of practice, seeing the composition before it happens will become almost instant. And while the guy next to you with a zoom lens is still fluffing around trying to get the perfect composition you would have had the shot in the bag and be on the lookout for the next one. It can be that quick.