[willis936]

It also assumes that your DHCP range is the top half of the last byte. That's a de facto convention in consumer routers, but not codified anywhere and the kind of thing that could change and probably isn't even correct for some routers shipping today.

[yardstick]

Definitely not codified anywhere, and not in any of the routers I’ve used (to be fair they are more prosumer).

The main dhcp server used in most routers, dnsmasq, also assigns IPs using a MAC algorithm by default for consistent IP addressing of devices in a LAN. You would need to explicitly configure it for sequential first come first serve.