At a minimum, AIDE should be configured to run a weekly scan.
To implement a systemd service and a timer unit to run the service periodically:
For example, if a systemd timer is expected to be started every day at 5AM
OnCalendar=*-*-* 05:00:0
[Timer]
section in the timer unit and
a Unit section starting the AIDE check service unit should be referred.
Rationale
AIDE provides a means to check if unauthorized changes are made to the system.
AIDE itself does not setup a periodic execution, so in order to detect unauthorized
changes a systemd service to run the check and a systemd timer to take care
of periodical execution of that systemd service should be defined.
ISA-62443-2-1-2009, Security for Industrial Automation and Control Systems Part 2-1: Establishing an Industrial Automation and Control Systems Security Program