Long enough?

 I've seen a few marathon training programs that incorporate an "over distance run", and others that incorporate a "practice marathon" as a long run. As it turns out, this may not be the best option for everyone, most especially first time marathoners. Basically, running for 26.2-miles puts a lot of stress on your body, regardless of pace. Since it takes a bit to recover, you're losing out on quality workouts. Even if you don't feel too bad, your muscles become inflamed from micro-tears, there is some cellular damage, and your immune system takes a hit. In reality, the majority of the training benefits associated with long runs occur between 1.5-2.5hrs in, so there's little point in running over 3hrs.