It looks like the default DHCP lease time is 1 hour. Because the lease must be renewed before the lease expires, I typically see hosts renewing anywhere between 1200 and 1500 seconds. That seems a bit excessive, although it isn't causing any harm. What's a few LAN packets among friends? 
The default leasetime in OpenWRT is 12h: https://wiki.openwrt.org/doc/uci/dhcp
What's the reason for having the AREDN default lease time at 1 hour?
The default leasetime in OpenWRT is 12h: https://wiki.openwrt.org/doc/uci/dhcp
What's the reason for having the AREDN default lease time at 1 hour?
So this setting actually has deep roots at the very very beginning of the mesh project, so the exact reason predates myself . It could of been intentional, or could of been just plain dumb luck (I would like to think the former though.)
A couple arguments I can make in favor of the 1 hour time:
1) The probability of a 'Highly mobile" device list (laptops come and go during an incident) requires faster ability to respond to changes in the locally connected systems.
2) Limited IP space range needs to be "freed" sooner than later (this is somewhat an extension of item 1, but is very important, if all leases are in use and yet to expire the mesh node can not offer the IP to another system)
Basically all the arguments I have for it to stay at the current 1h have to boil down to reacting to what is going on. In a home network that doesn't move that often and devices stay pretty constant a long lease isn't such a big deal, and is encouraged, in much more dynamic networks faster response matters.