In one embodiment, a device in a network determines behavioral profiles of a plurality of nodes in the network. The behavioral profile for a particular node indicates whether the node is an occasional transmitter or a periodic transmitter. The device identifies similarly behaving nodes based on their behavioral profiles. The device assigns groups of the nodes to uplink transmission windows based on their behavioral profiles. The similarly behaving nodes that are periodic transmitters are assigned to the same uplink transmission windows and similarly behaving nodes that are occasional transmitters are assigned to different uplink transmission windows. The device controls the plurality of nodes to use their assigned uplink transmission windows via target wake time values sent to the plurality of nodes.