Some years ago, 2004 by the looks of it, I had created a simple script (wrel) to get an idea of how reliable my wireless link was, and have since updated it with a slightly better user interface (it now has a progress guage) and it uses a sub-second interval when run as root. In particular, I wanted to get some impression of how often there was some sort of retransmission event. You can’t tell this from any link-layer, and I wanted something more general, in order to observe the spread of round-trip-times over internet links, wireless links, and even HomePlug (Ethernet over Power). Ping gives a useful metric for this.