Just ran 2:25 off a 12 week build (second marathon, first one was 2:41). I averaged 107 km per week.
Mileage: 84,94,104,82,106,116,135,118,135,145,87,81 km
Quality Sessions:
Week 1: 12x400 @ 75-70, 2x3k @ 3:26/km, 24k LR @ 4:08/km
Week 2: 3xmi-3x800-3x400 @ 5:39/2:32/71, 8k trail race + 10x200 hills, 26k LR @ 4:12/km
Week 3: 5xmi-4x200 @ 5:05/29, 10k tempo @ 3:30/km, 28k @ 4:06 w/ 8k @ 3:38/km
Week 4: 5x800-5x400 @ 2:28/70, 2x4k @ 3:25/km, 25k LR @ 4:24/km
Week 5: 6k-6xk @ 3:28/3:19-06, HM race: 73 min
Week 6: 10xk @ 3:15, 12k tempo @ 3:30/km, 30k LR @ 3:50 w/ 12k @ 3:28/km
Week 7: 6xmi @ 5:12-07 + 5x200 hills, 2x5-2x2-1k @ 3:30/km, 35k progression @ 3:51/km (4:25 --> 3:30/km)
Week 8: 15x400 @ 71-69, 5x3k @ 3:25-20/km, 28k LR @ 4:08/km
Week 9: 2x800-1200-mi-2k-mi-1200-800 (3:10-2:55/km, blew up and DNF'd 2nd set), 8-5k @ 3:35-3:25/km, 34k @ 3:46/km w/ 16k @ 3:29/km
Week 10: 7x1200 @ 3:53-47, 4x5k @ 3:30-3:23/km, 36k progression @ 3:50/km (4:10 --> 3:23/km)
Week 11: 15x3/1' @ 3:20/km (only did 3x3/1', felt terrible), 8k @ 3:24/km + 5x200, 20k LR @ 4:28/km
Week 12: 5k @ 3:30/km + 3x90" faster, 2:25 marathon!
Sure I'm training seriously, but volume is low and workouts aren't crazy...