I think we could all get up to a decent standard if we trained correctly (notice i said correctly and not hard!) the key points being what you want to achieve. I'm not a big fan of this big mileage theory, unless you want to run ultras, its about experimenting with what you can absorb, and doing specific sessions for what you want to race. I personally drink to much, eat to much junk food and dont train consistently enough, if i cut down the drinking and sorted my diet out and trained properly then maybe i would be half decent, but i cant be arsed.