Visiting the Data Section is, for all intents and purposes, the same as reviewing the Check Data menu which is available in the City Locations screen, the Hideout menu, the Airport menu, and the Observation menu. Note that the names of the options on the Data Section menu are slightly different from those on the Check Data menu, but they are essentially the same otherwise.
Visiting the Data Section costs no time off the clock in and of itself - however remember that it does cost 2 hours to go to the CIA Office, which means that unless you have business in the Intelligence Section or Crypto Branch, there's no point to visiting an Office just for reviewing data at the Data Section.
Press "ESC" to leave the Data Section and return to the CIA Office lobby. This costs no time off your clock.
For more reading, please see the Check Data article.