So, the two devices you refer to have no time-of-day clock, no network connection, no TCP/IP stack, and certainly no NTP clients.

Their testing on the enterprise-class equipment shows the difference that NTP makes, and with enterprise-class equipment comes wider deployment and more powerful models.

But most of the consumer units would not have this stuff. Surely, the manuals would describe how to set it up.

Counting mains power cycles is an adequate clock with a 0 of whenever it was last closed in. That 0 could conceivably be correlated to an hourly schedule if that process is automated. Not saying it’s common, but signals don’t have to come from the network.