Real-Time Phoenix: only the first 3 responses are displayed on the console (p.101)

Here is a scenario of cyclic sending messages and receiving responses via slowStatsChannel.
The transport accepts all 5 responses, but only the first 3 responses that meet the 10s interval are displayed on the console, as seen in DevTools.
My understanding is that a packet transaction has a lifetime, after which the packets are accepted but are not passed to the processing script. This is a tricky disconcerting point for those who are new to real-time network programming.