8. With a running group you are likely to plan your training in advance. Therefore, you are also likely to becoming better (which means faster).
9. You often get a cool shirt that tells you belong to a certain group. That's likely to give you more confindence in a race. Moreover, the running group guys are the cool ones!
10. Sometimes, there are not only meetings to train but also informational meetings. In most cases there will be professionals giving some lectures about different topics concerning nutrition, health and other topics concerning your sport. I thought in the beginning I won't learn anything new there but to err is human!