Combining your trick with the burst collection mechanism you could get both the lower power consumption of your approach plus the synchronization via the server. That effectively gives each Moteino an accurate synchronized clock.
Thinking more about it we could now move to a modified ACK based communication structure that would work with coin cells and that I had planned to use with an external WDT: nodes send their updates to the server, then sleep a second to recover the cell and wake up to receive an ACK with timestamp and commands from the server. Server sends a short ACK burst to ensure delivery (say 50ms). Node uses timer to sleep and then switches to RX for a short period to receive ACK packet from the burst.
Nodes still have a synchronized clock and can schedule their updates any time during the 5 minute window - much less risk of crowding.
I'd still have listen mode available on demand to be switched on when I need to work interactively with my nodes. Since it would no longer be on permanently we could move to a higher duty cycle, bringing the bursts down to maybe 500ms and make things really interactive.
Hey kabuki, if this works I might have to order another one of those Listen Mode Medals
