Greetings--I just purchased 20 week Marathon Training Plan and am excited about starting. I noticed that the duration of  endurance run workouts  never exceed 1:30.  I am aiming for a 3:45 marathon. So no longer duration runs in the weeks leading up to my race(20-21 miles) ?? I am assuming that strength/endurance/efficiency developed during the 20 weeks will be enough to carry me through that distance.

Also, I plan to do most of my training on trails because I find it more…