Dude, if I'm ever in a situation where I need to RUN 15+ miles, Plans A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y and Z have all gone horribly wrong15.55 miles.
It REALLY helps endurance in short 3-6 milers too. Longer runs simply allow you to go harder for longer on the short runs.Dude, if I'm ever in a situation where I need to RUN 15+ miles, Plans A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y and Z have all gone horribly wrong