This one surprises most everyone. After all just go to Runners World's Website and you can get a daily marathon prep schedule. Look at Jeff Galloway's book, Marathon and you will find daily schedules for individuals wanting to finish, to running 4:40 to 3:30 to 2:39. So you must be looking at me and saying..."What gives?" Are all these programs...wrong?
No...not really...but yes. These daily schedules are great guides...but they are guides...and useful as guides...but you need to learn to listen to your own body. Example: Its 90 degrees and humidity is over 90% and you didn't get a good night's rest because the air conditioner wasn't working and all week you felt stressed to do your runs as schedule...and you have to go out according to the schedule and run a 20 miler. Yea...right...it is a guide...do not let it lock you into something that could hurt you.
A few years ago, I started to take the week runs and list them on a piece of paper. During the week as my schedule permitted, I would run the workout that seemed to make sense for me on that day given everything else going on. The result was I felt so much better. Most schedules are designed with one long run, a few days off and a few normal run days. Not very complicated, unless you are going after a time and then you have additional things like 4x1 miles @ 4:30 pace...yea right. All that means is that you need to make sure you put rest days around those track workouts and long runs. But the principle is the same...you take control of the schedule and work it according to your needs. You will be happier in the long run.
Newton also had schedules but he argued for flexibility. We need to see these wonderful schedules not as straight jackets, but rather road maps to get us from point one to the finish line. So, keep using those schedules but do so with a little grace and understanding that perfection in following the schedule doesn't equal success in the race.