I leave mine on too. Been doing it as far back as I can remember with all my SLRs and now DSLR. I have my general kit lens on all the time now. So if I need to shoot something quick...just grab and shoot. I seldom would need a long zoom for shooting as you tend to look around tings nearer to you. I find the kit lens is the right one to use 90% of the time. And also since it fits my shooting behavour it is great since dust will have less means of getting onto my CCD due to my less frequent need to change lens or putting one on or off.