I think I had posted this previously...I'll try to elaborate more. I used a training schedule for my first marathon in 1997 thru Runners World. It was based on a weekly percentage 100% being your top weekly mileage, then cut back to 90%, then back to 80%..and long runs anywhere from 14 to 20 miles once a week usually on sunday...
Week 1: 32 miles total, long run 14 mi
Week 2: 36 miles total, long run 16 or 17
Week 3: 40 miles total, long run 18 to 20
Week 4: 36 miles total, long run 15 to 17
Week 5: 32 miles total, long run 14 to 16
Week 6: 36 miles total, long run 17 to 18
Week 7: 40 miles total, long run 20
Week 8: 36 miles total, long run 16 to 18
Week 9: 40 miles total, long run 20
Week 10: 32 miles total, long run 12 to 14
Week 11: 25 miles total, long run 10
Week 12: 20 miles total, long run 6 to 8
Then the Marathon!!!
I had normally built a base of running 25 to 30 miles a week for a couple of months before I started this training shcedule. When I trained I only did Cathe's tapes like once a week, mostly step. I was doing my own weightlifting, like her Pyramids and Slow & Heavy. I believe the weight training did help my endurance and prevented injuries. I have run 11 marathons and 1 50K. Didn't start with injuries til I turned 40...YUK! 44 now and yes injured. Achilles tendonitis...but hoping for it to heal so I can start training for another marathon, I did find them addictive!...Good Luck...

...Carole