It does depend on the job and your aspirations. The top jobs aren't found in newspaper ads. They are given to people whose names are put into the highly selective pool of possible candidates by those high up in the company. You don't even get to hob snob with those higher ups unless you have the right schooling and connections (which often start at your school).
If knowledge is power, yet we are not so quick to give just anybody power, why then should we be so free with knowledge?