The important thing isn't how long you spend off the bike (though unlike CFB I don't think a couple of weeks off does any harm) it is how you change the pattern of your activity. You can't train at high intensity all year round witout burning yourself out, so during the off season doing longer, less intense training makes sense. Lower intensity means that you can tolerate higher volume, and also rebuilds your aerobic fitness and gives a platform from which to ramp up the intensity again in the spring.