I'm a high school runner that runs on average 40 mpw. I got some Nike Frees 4.0 a couple months ago and I used them for track workouts and stuff. I used my old shoes (Saucony) for everything else.
My Sauconys ripped (it's gone through a lot of mileage) and so I'm not sure if I should now do all my mileage in my Nike Frees or buy another pair to do most of miles in, leaving the Nikes for speed workouts (usually 2 times per week).
Thanks!