USAJobs.gov is the worst job application site that exists. Plan on spending a few hours just filling out the application on USAJobs.gov only to find out that all the information you just filled out is irrelevant because the department or agency website will make you fill it out all again. You're better off filing for unemployment than applying for a federal job. They make the job requirements so specific that unless you have made such a niche career path choice, they don't want you.