A JSET marathon training program is quite different to most other running programs, so have a read below to find out the answers to some of the common questions about JSET running.
The original equation that JSET is based on claimed to be able to predict marathon performance to within 4min, only by knowing average weekly distance and average pace over the eight weeks before a race. However, this used data from a relatively small group of runners. In reality I've found the original equation has a consistent offset. For me it's -14min (I can always run 14min faster than the original equation predicts). For another JSET runner it's +10min (He's always 10min slower than the original equation predicts). Once you know your offset then you can use JSET to predict with exceptionally high accuracy. Most the time your offset can be calculated by looking at your training data over the last few years.
Cross training will probably help you run a faster marathon. But there is not enough data to know exactly how much faster a cycling / swimming / yoga session will make you. For this reason JSET only accounts for running training. The same goes for running on hills. Hills probably help but we don't know exactly how helpful they are.
That depends on your goal. If you're aiming for a 3h30min marathon you might only need to run 4 times per week, but if you're aiming for 2h30min you'll need to run every day. The training ring makes it easy to know how much you should be running. Once you've met your training load target each week, put your feet up. Until then, go out for a run.
Absolutely! There are numerous ways to fit running into a busy life. If it's possible, you might want to consider a run-commute. Many people go for a few miles at lunchtime. These are just two examples of easy ways to rack up the miles without using too much time from your non-running life.
The equation was originally designed for people completing a marathon between 2h45min and 3h30min, but I have found it works just as well down to to 2h28min. If you're looking to run slower than 3h30min, the equation becomes slightly less accurate (because lifestyle factors play a bigger role in your training) but the principle still works.
Although JSET was first designed for marathon training it now works for any distance from 5k-marathon.
JSET is far more flexible than most training programs. Rather than prescribing a distance and pace needed for each run, JSET uses aggregate data for the whole week to determine your training requirements.
Training for longer gives you a higher chance of achieving your race goal, so it's up to you how long you train for. Remember that as you get faster you will need more training in order to improve.