When the server is backing collecting data it will check the database for what was collected it will then go back and collect everything but Storage information.
For example the collections will go back and collect Exchange Tracking log information , IIS log information Lync CDR information as that data is stored historically in log files or a backend database. When it comes to storage information like Database sizes or Mailbox sizes that is real time data and is not stored historically so there is no way to go back and gather this information.
