Use of a front lens cap and a rear cap (when the lens is not attached to the camera) should be a matter of course. The front lens cap should be removed just before the lens is to be used for an exposure. As soon as the camera is no longer needed in a readiness position - or when the lens is removed and stored in the gadget bag - the protective caps should be re-attached!
Those who follow these rules will always have clear front and rear lens elements. This is the best guarantee for expensive lenses to render their very best performance in terms of brilliant images with high contrast, impressive detail sharpness, and rich shadow details.