This book starts off by breaking runners into categories from Novice to Elite. There are 7 categories (further broken down by age groups and gender), and any recent race time (from 5k all the way to marathon) can be used to help you find out where you fit. Glover explains the different training concepts to help you improve your times. He goes into a lot of detail about all of the important topics. He gives weekly mileage guidelines, talks about maintaining a running base (what % of your weekly mileage should be used as a base), and what paces you should be training at based on your desired race time. Although his advice is specific (and supported with examples of studies that have been done to prove how certain concepts work), all of his advice can be adjusted to fit the individual reader's level and goals. He gives examples of training schedules for the 5k up to the marathon for each category of runner, and tells you how to write your own schedule. He gives many examples of different types of speedwork, hill training, and tempo training so runners can add variety to their own schedules. He says how often each workout should be done on a weekly basis, and at what point they should be done in the training cycle. This is a great book, easy to read, and full of tips that can help you improve your time at any distance.
I used to do my daily runs at the same pace, and train without a plan. Last year I started training using the concepts explained in this book (speedwork, hills, long run distances), and I have been able to cut 13 minutes off of my half marathon time in less than 8 months. These training concepts are well known, but Glover customizes them to the reader's level, gives many different examples of each type of workout, and expains which workouts are best for the distance you are training for (For example, he says 1 mile intervals are better when training for the 10k up to the marathon, while power intervals and repeats will be more helpful when training for a 5k or shorter distance). This is a great book, and I wish I had read it sooner.