Multiple data transfer requests can be merged and transmitted as a single packet on a packetized bus such as a PCI Express (PCI-E) bus. In one embodiment, requests are combined if they are directed to contiguous address ranges in the same target device. An opportunistic merging procedure is advantageously used that merges a first request with a later request if the first request and the later request are mergeable and are received within a holdoff period that is dynamically determined based on a level of bus activity; otherwise, requests can be transmitted without merging.