[[!comment format=mdwn username="joey" subject="""comment 3""" date="2015-04-14T19:42:22Z" content=""" [period](http://hackage.haskell.org/package/propellor-2.2.1/docs/Propellor-Property-Scheduled.html) is not a cron job, it just modifies the Property to only do anything every so often. It's also possible to modify a Property so it only runs once. [flagFile](http://hackage.haskell.org/package/propellor-2.2.1/docs/Propellor-Property.html#v:flagFile) can be used to do that. But there are good reasons for propellor to default to checking all Properties of a system each time: * It means that most Properties are idempotent, which has many good features, like being able to recover from a crash. * If a system no longer has a configured Property, to fix it back to having the property it's supposed to have. * Or, if it can't be fixed, to tell you with an error message in red. * It keeps propellor mostly stateless; rather than having to record state about how it thinks a system is, which could diverge from reality, it just looks at how it actually is. """]]