Adrian Sevcenco writes:
moreover you can separately configure a service without modifying the .service file (which usually is linked in /etc/systemd) :
Possibly my information is out of date. I thought you were to put such service files in /etc/systemd/system and systemctl looks here first when told to enable a service (which is to say, a service file in /etc/systemd/system will supercede one in /usr/lib/systemd/system at the time of an enable command).
I know that /etc/systemd/system continues to work. I've been using it.