I gave up trying to analyze stuff like this soon after
systemd appeared, I just have a bunch of things in
my /etc/rc.d/rc.local file to restart various
services after a brief delay. Things like:
/bin/bash -c 'sleep 5 ; service stunnel restart' > /dev/null 2>&1 <
/dev/null &
/bin/bash -c 'sleep 7 ; service postfix restart' > /dev/null 2>&1 <
/dev/null &
...
All things which at one time or another failed to
start correctly, and I also have the opposite - a
script to fix things before actually rebooting
so systemd won't hang forever at reboot:
https://bugzilla.redhat.com/show_bug.cgi?id=1088619#c23