At least historically, Red Hat wrote
In Red Hat Enterprise Linux, the intended use for the /usr/local/ directory is slightly different from that specified by the FHS. The FHS says that /usr/local/ should be where software that is to remain safe from system software upgrades is stored. Since software upgrades can be performed safely with Red Hat Package Manager (RPM), it is not necessary to protect files by putting them in /usr/local/. Instead, the /usr/local/ directory is used for software that is local to the machine.
For instance, if the /usr/ directory is mounted as a read-only NFS share from a remote host, it is still possible to install a package or program under the /usr/local/ directory.
But, this suggests that you have a local filesystem /usr/local, mounted on a directory of the NFS filesystem /usr.
Did Red Hat really support mounting /usr/local as a local filesystem, at the correct point after the network was connected and /usr was mounted over NFS? And vice-versa at shutdown time? How was this implemented? Are there some interesting options e.g. of
mount which were required to implement this?
The RHEL init script for mounting network filesystems is called