In one embodiment, a parent node in a network observes time slot usage of a channel hopping schedule by one or more child nodes of the parent node to communicate with the parent node. The parent node also identifies high priority traffic from a particular child node. The parent node detects time contention for the high priority traffic based on an indication that at least a portion of the traffic has been rerouted by a particular child node to a different parent node. In response to detecting the time contention, the parent node adjusts a communication strategy used by the one or more child nodes.