Welcome to the second block of the "The Workday Grind " Marathon plan (8 weeks).
This Low-Volume build plan is mainly about the building on the aerobic endurance stressor. Which is just a fancy way of saying 'improving your bodies ability to withstand longer runs'. There is also a single day each week dedicated to improving your speed at VO2 max (maximum oxygen uptake).
The final block of training is the "The Workday Grind" Marathon plan (8 weeks). This is meant to build fitness and experience specific to your race goals, and taper you so that you're properly rested for race-day. This is only meant for athletes that have finished the initial 16 weeks of the marathon plan.
WARNING: Although heavy intensity workouts result in quick and significant gains, they can and often do result in injury. This is why it's important to NOT skip the lifting workouts of this plan. The lifting is specifically designed for injury prevention as well as performance enhancement.