/etc/rc.d/netwait needs to run after anything that might be required in order to start network interfaces. In my particular case, that was /etc/rc.d/bridge which is often required when using VNET jails. Adding "bridge" to the REQUIRE line fixed the long delay on startup for me. (Otherwise netwait would run before bridge.)
I think the NETWORKING target really needs to be split into two: INTERFACES to ensure that all of the required interfaces are present and configured, and keep NETWORKING as meaning "basic networking services are actually functional".