How much time do you need to visit the Cinque Terre? If you are going to hike all five villages you need 6 hours with a quick lunch.But plan to make a day out of it  and really  since  you are making teh effort to get there,

stay on the Liguria levante coastline for a a few days. In addition to the Cinque Terre there is teh Gold coast further north, ie the Italian Riviera.