Lots of people have told me that your hards days should be hard and your easy ones easy. If this is the case then, why even bother running on your easy days? If the main purpose is for recovery, surely you would recover better by not running at all and stretching etc? Likewise, how do you gain any fitness if you're running so easy that it's basically jogging?
This is probably a stupid question but no-one has been able to give me an answer that makes any sense.