I am wondering if after installing an update of a selinux-policy-* package you are using, do you need to reset all the labels in the system (i.e. fixfiles onboot) in order to keep the policy effective?
It may depend on which distribution you are using, but in Fedora (and therefore in most or all Fedora-derived distributions including Red Hat Enterprise Linux and CentOS) the
selinux-policy-targeted package includes a postinstall script with
fixfiles commands, so it should not be necessary.