I'm a subscriber to both Runner's World and Running Times. There are a lot of differences between the two magazines, because they are aiming at two different audiences. Runner's World is targeted towards the social runner, someone who's in it to get fit and maybe run their first marathon. Running Times is for the more serious runner, someone who wants to get faster.
This difference is also shown in their training articles. Typically, Runner's World shows a full 16-week training schedule, telling you exactly what days to do hills and what days to do repeats. Running Times, on the other hand, gives you workouts. "Try this progressive workout to boost your stamina." "Build speed with these stepladder intervals." I think this is why I've grown to prefer Running Times more and more.
It's been a long time since I've used a strict training schedule. When I planned my training for the Pittsburgh Marathon this past spring, I had sketched out the number of miles each week I wanted to run, the length of my long run and the speed workouts I planned (usually Yasso 800s).
If you think about it, how often is it really possible to strictly adhere to a trainings schedule? The bottom line is that real life gets in the way. There's always a workout here or there that you have to reschedule, tweak or cancel because of illness, injury or social commitments.
Also, you have to consider that the one-size-fits-all schedules that you find in Runner's World and other publications don't account for your individual situation. Are you used to high mileage or low mileage? Do you respond quickly to speed training? Are you injury prone? Do you have time to run four days a week? Five days a week? These things all influence how to get the most out of your training, and your training plan doesn't account for any of them.
Training without a plan takes experience and experimentation. This year I planned to peak to my weekly mileage at 50 for the Pittsburgh Marathon and 60 for Oil Creek. I barely hit 50 in the spring and only once eclipsed 50 this fall. I had sketched out a plan, but learned that while I was handling 40 mile weeks with no problems, 50 was a bit of a stretch. I remained flexible and now I know what to expect from myself.
Training for the HAT Run 50K in March, I've made plans to focus on endurance and strength - so miles, hills and no speedwork. My peak mileage will occur in late February/early March at around 55-60 miles per week and will do one run of 25 miles and about three between 20 and 24.
You don't need a detailed training plan to race well. You just have to know what kind of training works for you and go out and do it.