In general WordPress posts do not represent continuous process. They and their data capture the state of certain point in time (last edit).
While there is a WP Cron mechanism for scheduled and (optionally) recurrent operations, it’s poorly suited for periodic post manipulation. For a large amounts of posts it would take either excessively long running update routines, or excessive amount of short running but multiple events firing. Either has issues.
In a nutshell I would suggest instead of looking how to do this, you should look how not to. As comment suggests there might be easier to change what data precisely you store and work with it, than make recurrent changes to it.