When you have no upcoming races in the system, you are placed onto a form of maintenance plan with an eye on your goal settings, including your stated preferred distance (if any). The ethos of this, as the name suggests, is to maintain your current level of fitness. In normal circumstances this results in a fairly static level of training, though for some that level can be lower than they actually would like (with a slow and gradual increase in volume).
An issue here is that 'maintenance' can mean many things to many people. As such consequent plans may not always meet individual needs, which in themselves may change over time. It is our intention to capture additional information from users on their desires under this situation in the future in order to enhance plan generation.
In the meantime, for some people, it may be more appropriate to enter a dummy (virtual) race of an appropriate distance into the system, most commonly of 10 km to 10 miles. Furthermore, adjusting constraints (such as reducing speedwork) could be applied 'according to taste'.