How Samsung able to maintain secrecy of new device until launch

Today Samsung Galaxy S6 is launch date and there is no trusted leak you can find.
There are thousands of people involved to manufacture in Samsung Galaxy S6. Also there are lots of interest over the internet about this device since first teaser launched.
There is possibility that any insider of manufacturing unit can leak the images and specs.

I am wondering how Samsung or any other big company able to maintain this secrecy.