What Zwfit route planning strategies do experienced cyclists use to maximize their workouts, particularly for those seeking to target specific training goals such as VO2 max, lactate threshold, or endurance, and are these strategies influenced by the type of terrain, route length, or the presence of obstacles and climbs. Is there a preferred method of selecting routes, such as manually choosing specific segments or relying on Zwifts automated workout generation, and how do users balance the need for varied and engaging routes with the requirement for consistent and repeatable training stimuli.