this module is not clear

CronPlus does not by itself do anything at all, other than make some entries into the watchdog log. Rather, it is an extension module for developers that provides module hooks that run hourly, daily, weekly, and monthly. Drupal itself provides only the one hook_cron() function that is called every time the external system (or poormanscron) invokes the Drupal cron functionality.

There is no fixed time interval guaranteed by Drupal's hook_cron(). The site administrator can run it every twenty seconds, twelve times an hour, twice a day, or any other interval. hook_cron() may not even be run at fixed intervals -- for instance, the site administrator may run cron.php four times an hour during the business week but only twice an hour on weekends.

What CronPlus does is to keep track of these indeterminate hook_cron() invocations and then provide its own invocation of cronplus hooks once per hour, once per day, once per week, and once per month. The timing of these is not exact, but as long as hook_cron() itself is invoked at least once per hour, the timing of CronPlus hooks will be "reasonably" consistent over time.

CronPlus is a developer's tool that is useful for other custom modules that need to do something once per day, once per week, etc. But by itself, it doesn't do anything at all to the web site or its content.

I hope this helps to clarify.

Kind regards,

Syscrusher