Users might end up with more than one of those service enabled, through
admin mistake, or broken installation scriptlets, or whatever. On my machine,
I had both chronyd and timesyncd happilly running at the same time. If
more than one is enabled, it's better to have just one running. Adding
Conflicts will make the issue more visible in logs too.
DefaultDependencies=no
After=systemd-remount-fs.service systemd-sysusers.service
Before=time-set.target sysinit.target shutdown.target
+Conflicts=chronyd.service ntpd.service
Conflicts=shutdown.target
Wants=time-set.target time-sync.target