Usually, listener nodes only evaluate the node chain every time they register a change propagated from an input. These changes are either captured from the Data Model's own change handler (such as when one writes to a SyncField) or by forcibly changing the nodes in the node group (such as by adding a new node). However, when any node in the node group connected to the listener is marked as ContinuouslyChanging, the listener will forcibly update all inputs every update.