Appendix B of the NSA's polygraph regulation provides some insight as to why many NSA applicants may receive as many as three polygraph sessions: the NSA's chief for security clearances has the authority, "with the concurrence of a
certified polygraph supervisory official," to bring an examinee back for as many as three "tests." A fourth examination requires a decision by the Director of Security, and any further examination(s) requires a decision by the Deputy Director for Administration.

Making applicants submit to the full three polygraph interrogations that require no special approval would enable the NSA polygraph unit to achieve the fullest level of employment for itself.