The marathon punishes under-preparation more severely than shorter races because of glycogen depletion — the body typically stores enough glycogen for roughly 30-32km of running, which is exactly why "the wall" is such a well-known phenomenon specifically at that point in the race, and why the long training runs in these plans exist to teach the body to spare glycogen and burn fat more efficiently at race pace.

The taper is often the psychologically hardest part of marathon training precisely because it feels counterintuitive — reducing volume right when race day approaches triggers real anxiety in many runners ("taper anxiety" is a genuinely common, well-documented experience) even though the physiological benefit of arriving fresh is well established and consistently outperforms continuing to train hard into race week.

Because marathon plans run 12-20 weeks, life-schedule realism matters more here than for shorter training blocks — illness, work travel, and minor niggles are near-certain to happen somewhere across that span, which is why experienced coaches build in buffer weeks and flexible scheduling rather than treating any single missed session as plan-ending.