That's one of the greatest questions of all times, if a beginner (like 6months to 1year) could handle doing high mileage while benefiting from it and not getting injured, should said 'beginner' do a high mileage approach to training?
Or could it maybe slow his progress somehow, even if he is recovering well and being able to do 2-3 (mostly 3) workouts and a long run per week?