Although marathons are 26.2 miles (42.2 kilometers) long and take even world-class marathoners over 2 hours to run, athletes who train by running 90 minutes a day fare better in marathons than do those who train by running 120 minutes or more a day.
Background
Marathons take at least 2 hours to run.
Surprising Claim
It's better to train for a marathon by doing 90 min runs each day than by doing runs of 2+ hours.
Evaluate / Goal
Given that ... the race they're training for is 2+ hours
Why is it that ... optimal training is only 1.5 hrs?
Maybe you burn yourself out if you practice the full-length thing too much (hint-hint: LSAT students, don't take test after test as your form of practice)