I've been coaching at the collegiate and HS level for over 25 years and what I've noticed (myself included) is that over the years we coaches and runners have increased the weekly mileage we expect from our athletes.
I have never seen a study that confirms that increased mileage provides any real benefit for 800m runners and I will go out on a limb and include the 1500/mile.
Why has this happened? I think many people just began to rationalize that if 50mpw was good 70mpw is better and hell 100mpw is even better. Then when we coaches would get together for a beer or attend conferences we'd hear that so and so who just won was doing huge mileage and suddenly we began to equate more mileage must be the reason.
I believe that there is a point where the additional mileage provides little or no measurable race time improvement and increases levels of fatigue, injury and sheer boredom (especially in younger runners) that you should reduce mileage.
The issue at hand is that every athlete is different some 800m/1500m runners need more aerobic strengthening than others so the cookie cutter recommendations are difficult to use.
Since the question was about the 800m I'm going to assume this is from a college or HS age runner rather than an older/hobby distance runner I till go on a tangent here and recommend this person concentrate on running as many races as possible this season and have someone record his splits every 200m. After 5-6 races he should see a trend which will help him determine where he needs to improve.
Last bit of advice: Don't lose sight that you are training to race not just training for the sake of training.