Science, to me, is quite often a restriction. Science DOES sometimes give us concrete proof that it's good to do cerain training, etc. But when you hear numbers, very reason why you believe it as a concrete proof, can be very limiting. It would give you the reason why you will never going to make it as a distance runner. You only have 50% of slow twitch muscle fibers. No good trying to become a marathon runner. If I remember it correctly, didn't Don Kardong record 50/50 slow/fast twitch ratio? Thank God he never let it decide his athletic career (otherwise, he would have not become a marathon runner and we would have never enjoyed his entertaining writing skill...). At some other thread I saw someone asking a training plan to be a good marathon runner and gave a hypothetical number of 26 seconds for 200m. Some wise man jumped and snapped; "Sorry, you're not fast enough to be a fast marathon runner..."
Planning on your training schedule based on purely science is, to me, like driving a car by only checking with rear-view mirror. Science has provided the reason why some workouts worked, why high altitude training helped, why taking an easy day after a hard anaerobic workout helps... But it is very rare that doctors (not exercise physiologist/coach) come up with some innovative training method. Before you decide not to exceed 73 miles a week because anything beyond that is "scientifically proven" to be junk-miles, get out and run 74 miles a week and see it for yourself. It may work differently for YOU.
My cholesterole level is a bit high. But I never quite bought into this high cholesterole = heart disease theory. Too many exceptions and too many unknowns. Arthur, after running thousands and millions of miles, had rather high cholesterole level and of course he ate red meat at least once a week (probably more...). Living up to 87 the way he did ain't too bad. Of course, now recent study is showing that things a bit more complicated than previously "proven"... I still restrict my bacon intake though!
Now Lydiard never said this but I'm pretty sure he would agree; "If in doubt, forget numbers!"