What is "Old School". Did someone find a new short cut to success?
Your post leaves many questions.
What are your goals? Are you running for fitness? Are you running to set a new PR? Are you training for a marathon? Are you a triathlete? Do you have something against running? What do you call high mileage?
40 mpw isnt too shabby....thats 2000+ mile per year.
If your running 40 mpw consistantly, which I doubt, then running 4 days a week or 7 days should'nt matter. If your just increasing your mileage and are just hitting 40 mpw then I would suspect some aches.
Nobody should run through pain.....achy, tired, sluggish..thats different. If your adding miles or intensity then you should be feeling a little achy and tired. Build for 3 weeks then rest.
40 mpw is about the most I would recommend anyone to run on just 4 or 5 days per week.
Those high mileage everyday runners are the ones in front of the pack. The only thing "Old School" about them may be there shorts.
Runners Run