This is a simple plugin that is mostly intended for developers. Basically, Q2A has no support for cron, although it allows its integration. However, configuring a cron process is something the average user does not know how to do. So I thought that, although cron is ireplaceable, a workround could be implemented that would work for most scenarios in which cron is needed.
So suppose you need to perform an action. Let's take, for instance, a table clean up. You could perform a DELETE statement on every request. Or maybe you could implement a counter that would execute the DELETE statement after a given amount of requests, in order to decrease server load.
Well, this plugin does exactly that. It fires an event after a given amount of requests. So all it is needed is to register an event module and make sure it listens to the event the plugin fires. This way, you just need to focus on the actions you need to perform (the DELETE) and how often you want them to be run (every 400 requests).
Additionally, the plugin can fire events on a daily, weekly and monthly basis. These events are, again, generated based on a request, however, they are limited to run only once per time period.
Again, the plugin does not care at all about time. Only about server requests, which may or may not be the same for the actions needed by other plugins.