I am training for my first marathon, been running 6 days a week, about 40 miles per week for 6 months (running between 20-3- mpw for 2-3 years prior). My long long run is Sunday, speed session Wednesday, mid distance run Friday, and 2 more easier days. Where would place a day off?
Monday after long run
Tuesday before speed session
Thursday after speed session
Saturday before long run