Interesting - I normally equate such a job with wanting to run at a particular time each day. In the example you gave, this would start at midnight when you first kicked off the job. However if this were to be deployed anywhere that observes daylight savings, then in a few months your script will start running at a different time (probably 11pm or 1am) depending on which hemisphere the country is in. Then (roughly) 6 months later it will swap back. But it will always be a 24 hour period after the last run.