USAJobs.gov is a clearing website for federal agencies required to advertise jobs to the public by law. It is nothing more than a formality, because the agencies are under no obligation to 'close' the jobs, meaning they don't come back to inform the public that a selection has been made. This is why so many referrals literally stay 'green' for years after the closing date.
For every 9 out of 10 jobs, the hiring official has already picked someone internal to the agency. One specific example can be as simple as this: It's easier to train someone internal who already holds a security clearance who will not require long, expensive background checks, than on-board a new person and do the paperwork.
The remaining 1 out of 10 jobs can be broken down in this way:
Half (0.5) will lead to an interview, where the agency is either looking for a well qualified external candidate, who will add value to the agency based on experience and qualifications, and compare them to their internal candidate of choice, or eliminate you with impossible questions that only the internal candidate would be able to answer. It's a win-win game for the agency, and again you are never informed following the interview.
The last 0.5% are jobs where no one wants to go, with a high turnover because you are sent to some lonely outpost of the 'federal empire' as I like to call it. This is the category that I've been in for the last 14 years, even though I'm a veteran. The Federal Government is a closed world, and by all means a good one if you are on the inside, but even being on the inside does not grant you any special favors when using this website to apply for higher managerial positions or even lateral transfers.