Methods, systems, and devices for wireless communications are described. A user equipment (UE) determine that at least one packet of a set of packets for a downlink message is unsuccessfully received at a radio link control (RLC) layer of the UE due to a specific situation of a set of specific situations and may transmit the NACK message based on the missing packet (s) on an as needed basis rather than waiting for a timer to expire (e.g., a fast NACK mechanism). In some examples, the specific situations may include the UE missing packets after a measurement gap, missing packets based on wake up latencies for a discontinuous reception mode of the UE, missing packets due to interference from reference signals transmitted by neighboring cells, missing packets due to the UE not decoding retransmissions that have a same redundancy version (RV) of a downlink message, or a combination thereof.